So I understand that the enhancement bonus of the black blade goes up, but you can also increase it by using your arcane pool correct? Does it override the original bonus or does it stack?
At 1st level, a magus can expend 1 point from his arcane pool as a swift action to grant any weapon he is holding a +1 enhancement bonus for 1 minute. For every four levels beyond 1st, the weapon gains another +1 enhancement bonus, to a maximum of +5 at 17th level. These bonuses can be added to the weapon, stacking with existing weapon enhancement to a maximum of +5. Multiple uses of this ability do not stack with themselves.
The only alteration the bladebound archetype makes to the magus arcane pool is the amount of points in it. The archetype does not change what the arcane pool can or cannot do. The blackblade does have its own pool that can be used to power specific powers of the blade. So, the magus can use its arcane pool to boost the enchantment bonus of the blackblade to a maximum of +5.
Yes the bonuses stack.
However there are some restrictions.
The Black Blade itself only ever gets +x bonuses. The bonuses that the blade automatically gets can't be replaced with Keen/Flaming/etc, they're all just +x. So a level 3 Black Blade has a +1 Enhancement bonus, a level 5 BB has a +2 enhancement bonus, etc, etc.
The Black Blade also cannot be used to craft any other properties onto it .
However you can use your Magus Arcane Pool to add enhancement bonuses or other enchantments to the weapon.
Remember that the usual restrictions still apply. So you cannot have a +x enhancement higher than +5. So a 17th level Magus with a +5 Black Blade and another +5 enhancement bonus from their Arcane Pool can't give their weapon a +10 bonus, or even a +6 bonus, they'd have to use their Arcane Pool ability to add other enchantments to the weapon. The 2 exceptions to this are the BANE property and the FURIOUS property , so if you were a Barbarian-1/Magus-15 fighting some Orcs, and you were raging and had the Bane Blade Acrana it would be possible to get your weapon to a +9 enhancement bonus ... but that's not a usual state of affairs. The Bane Blade arcana is something a Magus can use though, so it's worth remembering.
The other restriction to note is that a weapon can never have a higher total equivalent bonus than +10. There is no specific restriction on the number of enchantments you can have besides going over the +10 and needing at least a +1 Enhancement bonus , but that +10 limit applies. So you can have a +4 Flaming, Frost, Shock, Keen weapon , or you can have a +1 Flaming-Burst, Icy-Burst, Shocking-Burst, Keen weapon , and either of those would be fine. For the Bladebound this is unlikely to matter as you have a guaranteed +5 from the Black Blade itself, but remembering that you can't go over the +5 Enhancement bonus is important.
So with that in mind:
At level 1 you can enhance your +0 weapon to a +1 weapon with your Arcane Pool .
At level 3 your weapon becomes +1 and you can enhance it with another +1 to +2 with your AP.
At level 5 your weapon becomes +2, and you can enhance it with another +2 to +4 with your AP. At level 5 you also gain the ability to add special abilities to your weapon in place of straight +x enhancements when using your AP, at equivalent cost to your AP. The abilities you can use are outlined in the Magus class entry.
At level 9 your weapon becomes +3, and you can enhance it with another +3 to +6 with your AP. As I said above a weapon can't have a +6 Enhancement bonus so at least 1 point of the bonus from your AP has to be used on a special ability or abilities.
At level 13 your weapon becomes +4, and you can enhance it with another +4 to +8 with your AP. At least 3 points of the bonus from your AP has to be used on special abilities.
At level 17 your weapon becomes +5, and you can enhance it with another +5 to +10 with your AP. At this point your weapon has maxed out it's enhancement bonus so the entire bonus from your AP has to be used on special abilities.
One note on this that new players often misunderstand, a level 5 Magus can enhance their +2 weapon to +4 by expending ONE AP point. You don't have to spend 1 AP point per bonus, it's just 1 point per use. At level 17 you spend 1 AP point and you get a +5 bonus equivalent to add to your weapon.
Finally, the Black Blade itself has an Arcane Pool, and has abilities it can add to the weapon. As far as I can tell none of these abilities are counted as equivalent to +x abilities, so they are irrelevant to the limitations listed above. If your blade has the points to spend it can add them.
EDIT: Oh one thing I forgot to mention: The AP bonus doesn't stack with itself. You can't use 2 AP points to give yourself +2 twice for a total of +4, for example. It doesn't work. That's explained in the Magus class. I just figured I'd covered everything else so I might as well add this as well.
It makes sense if you compare it to just the regular magus with a regular magic sword. And in a lot of campaigns the regular magus will have those enhancement bonuses from a regular magic weapon earlier than the blade bound.
The black blade is mostly a fun vanity item, though it can be handy in campaigns that are low on magic items. And it’s nice for knowing you’ll have a good option for any weapon specific feats at every character level. Still, don’t be shocked if you end up with a main weapon that outclasses your black blade at certain levels.
Still, don’t be shocked if you end up with a main weapon that outclasses your black blade at certain levels.
Since the Black blade is intelligent, a magus would typically not want to upset it by doing that, and unless the other weapon is of the same type, the feats used to get better with the Black Blade will still allow it to outclass the "other blade"
Still, don’t be shocked if you end up with a main weapon that outclasses your black blade at certain levels.Since the Black blade is intelligent, a magus would typically not want to upset it by doing that, and unless the other weapon is of the same type, the feats used to get better with the Black Blade will still allow it to outclass the "other blade"
The personality of the Black Blade is up to the player and GM. While it could be jealous, it may just be happy that its guiding purpose is being accomplished at all. I could even imagine one who gets upset at being used for day to day activities, considering it's purpose to be the only completely correct time to use it, and begrudingly letting you use its power more regularly just to keep you alive.
I would not call a black blade a vanity item. While it’s enchantment bonus or properties may be exceeded by a normal magic item it has several properties that can make it more powerful than a normal magic weapon.
Unbreakable means that while the black blade has at least 1 point in its arcane pool it is immune to be sundered.
Black Blade strike is an untipped bonus so stacks with the enchantment bonus to damage. This allows the damage bonus to exceed the +5 limitation. At 17th level the magus can be getting a +7 bonus to damage.
Energy attunement allows all the damage the magus deals to be converted to the chosen energy type. This can allow the magus to bypass DR of creatures and even target vulnerabilities. For example, a magus fighting a pit fiend could convert the damage to electricity bypassing the need for a silver and good weapon. If the magus is fighting something with the fire or cold subtype, they could convert the damage to the opposite and deal an extra 50% damage. Converting the damage to force allows you to do full damage vs an incorporeal creature. How many available at low to mid-level can match this?
At 9th level the magus can teleport the blade to him from up to a mile away. This makes it very difficult for the black blade to be lost or stolen.
How many 9th level characters have a +3 unbreakable weapon that is nearly impossible to lose that can deal full damage to almost any creature.
The black blade is also fully aware of its surrounding so can give the magus an extra perception roll to notice things he might miss.
The damage bonus of the strike is negligible compared to all of the other sources of damage the magus brings. I can't think of a situation where it would knowingly be worth the pool cost.
Unbreakable just prevents the "broken" condition. The blade can still be destroyed by taking enough damage.
Energy attunement is actually pretty strong, letting you ignore DR in a novel way. But you are very limited in how often you can use it.
The personality of the Black Blade is up to the player and GM. While it could be jealous, it may just be happy that its guiding purpose is being accomplished at all. I could even imagine one who gets upset at being used for day to day activities, considering it's purpose to be the only completely correct time to use it, and begrudingly letting you use its power more regularly just to keep you alive.Still, don’t be shocked if you end up with a main weapon that outclasses your black blade at certain levels.Since the Black blade is intelligent, a magus would typically not want to upset it by doing that, and unless the other weapon is of the same type, the feats used to get better with the Black Blade will still allow it to outclass the "other blade"
Sure, that was a side point, the main point being that since you probably have Feats like Weapon focus etc with your black blade, unless the other weapon is of the same type, losing the bonus from those feats is usually not worth whatever cool thing the alternate weapon has.
The black blade is mostly a side-grade (or a slight downgrade) to a normal magic weapon. It has some nice abilities, but is much less customizable and there are limitations as to what you can add using the magus arcane pool.
The biggest benefit (IMO) is being able to invest more into other magic items (not necessarily other weapons) because of the auto-scaling of the black blade.
One possible workaround is to dip one or two levels in occultist and make the black blade your Transmutation implement ("belt, boots, sandals, vest, weapon"). The legacy weapon base focus power for Transmutation allows the magus/occultist to add any "+1 equivalent" ability to a magic weapon by spending 1 focus point.
A spell warrior skald (or someone with a dip in it) is also useful to have in a combat-focused party to add abilities to multiple PCs via the enhance weapons weapon song. Skald is a Cha-caster, not an Int-caster like magus or occultist, so it might be more appropriate for a different character than the magus.