There are certainly rules for cursed items (in the Magic Item chapter of the core rulebook), but nothign quite like you describe as far as I know.
I would definitely use the existing rules as a starting point though.
I once played an old hag of a witch named Hama who specialized in curses and cursed items. After talking to my GM, I was allowed to intentionally make a cursed item, using the same costs and Spellcraft DC/caster level as the non-cursed magic item I was trying to emulate.
If I failed my check I either ended up with a cursed item that didn't function as intended, or a perfectly functional non-cursed item.
You can also find the official rules for cursed items here and here.
The sword you describe could be a cursed weapon that has a requirement (as per the cursed item rules). The requirement that best fits what you describe is the following rule:
The character must sacrifice some part of her life energy (2 points of Constitution) one time. If the character gets the Constitution points back (such as from a restoration spell), the item ceases functioning. (The item does not cease functioning if the character receives a Constitution increase caused by level gain, a wish, or the use of a magic item.)
Otherwise, it would function as a normal magical sword. You could even continue to describe it as "sucking the character's blood each day" much like you said.
My players want to create magic Items, and are willing to accept nasty penalties to reduce cost and add story depth. Are there rules for this (or will there be soon)?
One of my Players got an idea from some book that his weapon would require his blood (1d4 damage) each day, to activate its powers. Would heal overnight, but couldnt be healed during the day without losing the weapons powers.
Thats just one example; I could think of many others. What would these kinds of penalties do to the price of the item?
The rules for creating cursed magic items exist but there are no specific rules for creating your example item, no.
Now with that said it should be easy to come up with a few new weapon properties that are fueled by the item wielders blood or soul or some such. Here are a few examples.
Bloodbane: As a swift action, the wielder of a Bloodbane weapon can imbue the weapon with power by sacrificing any number of hit points. A Bloodbane weapon remains imbued until the next time it successfully strikes a foe. Any target struck by a Bloodbane weapon that has been imbued with power takes an additional amount of damage equal to the amount of hit point sacrificed to imbue the Bloodbane weapon with power. A successful fortitude saving throw, DC 16 + wielders Constitution modifier, halves this extra damage. Creatures without a Constitution score are immune to this extra damage.
Moderate necromancy; CL 8th; Craft Magic Arms and Armor, vampiric touch; Price +1 bonus.
Metabolic Celarity: A Metabolic Celerity weapon begins each day with a single charge. As a full round action the wielder of a Metabolic Celarity weapon may sacrifice 2d6 hit points to add a charge to this weapon. These hit points cannot be healed until the these additional charges are expended. A weapon with the Metabolic Celarity property can never hold more the 3 charges at once.
As a swift action the wielder of a Metabolic Celerity weapon may expend charges from his weapon. The benefits depend on the number of charges expended.
1 charge - You gain the benefits of the Haste spell for one round
2 charges - You gain the benefits of the Haste spell for one round and gain two additional attack at your highest BAB
3 charges - You gain the benefits of the Haste spell for one round and gain three additional attacks at your highest BAB
In addition the wielder of a Metabobolic Celerity weapon may expend three charges as a swift action whenever he is nearby when a Timestop spell is cast. If he does, he may make a fortitude saving throw (using the casters normal DC for 9th level spells). If successful he is Slowed (as the spell) for the duration of Timestop rather than frozen and may be targeted and damaged normally.
Moderate transmutation; CL 10th; Craft Magic Arms and Armor, haste; Price +2 bonus.
Now with that said it should be easy to come up with a few new weapon properties that are fueled by the item wielders blood or soul or some such. Here are a few examples.
Bloodbane: As a swift action, the wielder of a Bloodbane weapon can imbue the weapon with power by sacrificing any number of hit points. A Bloodbane weapon remains imbued until the next time it successfully strikes a foe. Any target struck by a Bloodbane weapon that has been imbued with power takes an additional amount of damage equal to the amount of hit point sacrificed to imbue the Bloodbane weapon with power. A successful fortitude saving throw, DC 16 + wielders Constitution modifier, halves this extra damage. Creatures without a Constitution score are immune to this extra damage.
Moderate necromancy; CL 8th; Craft Magic Arms and Armor, vampiric touch; Price +1 bonus.Metabolic Celarity: A Metabolic Celerity weapon begins each day with a single charge. As a full round action the wielder of a Metabolic Celarity weapon may sacrifice 2d6 hit points to add a charge to this weapon. These hit points cannot be healed until the these additional charges are expended. A weapon with the Metabolic Celarity property can never hold more the 3 charges at once.
As a swift action the wielder of a Metabolic Celerity weapon may expend charges from his weapon. The benefits depend on...
Those weapons are SERIOUSLY broken. What is to keep someone from imbuing a bloodbane weapon with a thousand "blood points" over time, only to hit the BBEG for 500 damage? The Metabolic Celerity is almost as unbalanced, as getting three additional attacks at your highest attack bonus in exchange for a couple of hit points is stupidly powerful.
Sure it's easy to come up with new properties, but they have to be balanced to existing properties or else no one will ever use anything else.
+1 or +2 modifiers? Really?
The Metabolic Celerity weapon is a +5 minimum, and I think it would better fit a major artifact.
There are rules for redcing the costs, but if you go the rout of the cursed items dont let them be false curses.
So if the player gets his blood drinking sword make it Drain not Damage and dont let it heal through natural healing. (or even heal at all while the sword is being wielded)
There are rules for redcing the costs, but if you go the rout of the cursed items dont let them be false curses.
So if the player gets his blood drinking sword make it Drain not Damage and dont let it heal through natural healing. (or even heal at all while the sword is being wielded)
That's why I pointed out that his sword DOES exist within the rules, just as I've described above.
EDIT: And to answer the OP's question, such a sword would cost the same as a normal sword without the curse effect.
Therefore a +1 longsword would cost 2,315gp. The same longsword with the curse that drains 2 points of your Constitution to continue functioning as a magic item also costs 2,315gp.
Those weapons are SERIOUSLY broken. What is to keep someone from imbuing a bloodbane weapon with a thousand "blood points" over time, only to hit the BBEG for 500 damage? The Metabolic Celerity is almost as unbalanced, as getting three additional attacks at your highest attack bonus in exchange for a couple of hit points is stupidly powerful.Sure it's easy to come up with new properties, but they have to be balanced to existing properties or else no one will ever use anything else.
+1 or +2 modifiers? Really?
The Metabolic Celerity weapon is a +5 minimum, and I think it would better fit a major artifact.
They SERIOUSLY aren't.
When was the last time you had a character with even 500 hp? The most you're likely to see is 100 save for 50. Unless you were thinking he could just keep pooling them? He can't. I would never even buy this weapon cause it isn't even good. There are so many better things you could do that wouldn't constantly make your cleric hate you for wasting their actions. So yeah +1...really. Or even just +2500 gp.
The Metabolic Celerity however IS very powerful. Maybe a +3 but it isn't a +5. All Metabolic Celerity is every going to do is make one of your full attacks (which are already really powerful) uber, once per encounter. That's powerful but not even close to game breaking. But sure +3. Making this a +4 or +5 would make it useless as no one would ever get it, because a Flaming Frost Shock +1 (+4 all together) Long Sword is still better than a +1 Metabolic Celerity Long Sword.
They SERIOUSLY aren't.
When was the last time you had a character with even 500 hp? The most you're likely to see is 100 save for 50. Unless you were thinking he could just keep pooling them? He can't. I would never even buy this weapon cause it isn't even good. There are so many better things you could do that wouldn't constantly make your cleric hate you for wasting their actions. So yeah +1...really. Or even just +2500 gp.
The Metabolic Celerity however IS very powerful. Maybe a +3 but it isn't a +5. All Metabolic Celerity is every going to do is make one of your full attacks (which are already really powerful) uber, once per encounter. That's powerful but not even close to game breaking. But sure +3. Making this a +4 or +5 would make it useless as no one would ever get it, because a Flaming Frost Shock +1 (+4 all together) Long Sword is still better than a +1 Metabolic Celerity Long Sword.
There is nothing saying he can't pool the hit points over time. The text even implies that he could, when it says there is no limit.
I overlooked the daily limitation of the Metabolic Celerity ability though. Three bonus attacks per day (even if taken all at once) isn't nearly as broken as I initially thought (though still very powerful).
There is nothing saying he can't pool the hit points over time. The text even implies that he could, when it says there is no limit.
I figured it would just by understood. I guess I wasn't clear. That's my fault.
I overlooked the daily limitation of the Metabolic Celerity ability though. Three bonus attacks per day (even if taken all at once) isn't nearly as broken as I initially thought (though still very powerful).
RAGE!!! YOU MUST BEG FOR FORGIVENESS FOR DARING TO MAKE A MISTAKE IN MY PRESENCE!!!!RAWR!!
Don't worry about, its all good.
Without hard and fast rules for what you want, it's going to be your call. You should just do your best not to let them get away with things that don't really impose penalties. Losing your sense of smell and taste, or smelling and tasting bad (these can work in their favor, too if you're not careful!) are not really penalties.
Grafts are relatively common in 3.5 books. They often require costs, such as was mentioned with the Constitution penalty. Permanent hit point loss, ability score penalties, a chance of being afflicted with some sort of condition (IE: sleep, or blinded) are all good ones, I think. HP drain over time sounds good too, but it's more easily overcome than conditions and such, and means less to characters with high AC and/or saves who don't take as much damage, or take it less frequently.
Best of luck with this. It sounds fun. :D