For the artificer, take a page from the bladebound magus. For his rod, give it an arcane pool. He can spend points from the arcane pool to create magical effects for the rod.
Example:
"This rod is imbued with pure arcane power, and a skilled artificer can tap into it. The rod has an arcane pool equal to 1/3 the artificer's level, plus his intelligence modifier, if any. The arcane pool can be used in the following way:
Swift Action: 0 points (so long as it has at least 1 point left) the rod can be changed into any weapon, tool, or shield which can be held in one hand. It is always of masterwork quality. If the rod has 1-3 points, it counts as only being masterwork. If the rod has 4-5 points, it counts as being silver. If the rod has 6-7 points, it counts as being both silver and cold iron. If the rod has 8+ points, it counts as being adamantium.
Swift Action: 1 point to add +1 enchantment bonus to the item for 1 minute. This ends early if the rod changes shape. Up to 5 points can be used to make the rod a +5 weapon.
Swift Action: 1 point to add any +1 Weapon or Armor Special Abilities to the item for 1 minute (except Bane). The rod must have already been made a +1 weapon or shield for this to work. This ends early if the rod changes shape.
Swift Action: 1 point to add any +2 Weapon or Armor Special Abilities to the item for 1 minute. The rod must have already been made a +2 weapon or shield for this to work.
Swift Action: 2 points to add any +3 Weapon or Armor Special Abilities to the item for 1 minute. The rod must have already been made a +3 weapon or shield for this to work.
Swift Action: 3 points to add any +4 Weapon or Armor Special Abilities to the item for 1 minute. The rod must have already been made a +3 weapon or shield for this to work.
Swift Action: 1 point to continue existing effects for 1 minute.
Note: Adding an enchantment bonus and a special ability to an item can be done during the same swift action.
So lets say that your Artificer is lvl12 and has Int18. That gives him an arcane pool of 8.
He can walk around and make any adamantium weapon or shield that he wants, using a swift action. That's pretty useful.
But he then goes up against a skilled warrior and he isn't sure that he can win. He decides that he wants to make his rod a +1 battleaxe. He spends a point and it is now a cold iron/silver +1 battleaxe for 1 minute, because the rod no longer has enough arcane points to stay adamantium.
He defeats the warrior. And is feeling pretty good. But then he finds that behind the warrior was demon! He thinks to himself that his weapon is already cold iron. But what he wants is for the weapon to be holy, for the 2d6 points of damage, level drain, and DR. His weapon is already +1, but holy is +2 bonus. So he does a swift action to increase his bonus to +2 and to add Holy, which costs him 2 more arcane points. He is now down to 5.
He is fighting the demon, and his time is running out. So he uses a swift action to extend his bonuses for 1 extra minute. He is down to 4.
He defeats the demon, and the enchantment runs out. His battleaxe now only counts as being silver.
-----
Yes, this means that he can nova through his arcane points really fast. But you know what? He can make a weapon or shield into exactly what he needs for any situation. That is really useful. Got an enemy who is weak to fire? Your weapon is now flaming. The enemy next to it is immune to fire but is weak to cold? It is now icy. That's versatility right there.
For the staff, I'd say let it store spells.
Counts as being an adamantium staff. It can store up to his level in spells per day, and can release spells stored as a move and/or swift action. The spells can only target himself, and does not provoke. The spell holds the spells until the magus recharges his magic after resting. Even with the staff, the magus cannot cast the same spell twice in one turn, nor can the staff cast anything which would cause a touch attack (such as shocking grasp).
So he is lvl12. He can hold up to 12 levels of spells in total, and only up to 3 spells. He decides that he is going to cast Cat's Grace (lvl2), Elemental Body I (lvl 4) and Fireshield (Lvl4) in the staff.
Combat starts. He first casts shocking grasp on himself with a standard action, then uses a swift action to cast Fireshield on himself, and uses a move action to close with the enemy. The enemy gets zapped, but the magus now has a defensive spell up.
The combat ends, and he still has Cat's Grace and Elemental Body I in the staff. He has used up 10/12 possible levels worth of spells for the staff. So he decides to cast Bladed Dash (lvl2) on the staff. The staff now has held 12/12 possible levels.
Another fight comes up. The magus decides that this is it. He has to nova the enemy down *now*. So he uses his standard action to cast shocking grasp. He uses his swift action to cast Elemental Body I from the staff on himself. And he uses his move action to cast Bladed Dash, making him dash right up to the enemy and hit him hard.
The next round of combat comes around, and the enemy is reeling. The magus wants to cast shocking grasp and use his spell combat. He does so, and uses his swift action to use up the last charge in the staff, giving himself cat's grace. The extra bonuses help him nova the enemy down.
As you can see, the Magus nova'd two enemies, with insane action economy. However, he did end up using up most of his spell slots. This could have the effect of getting your magus to cast spells he otherwise wouldn't have the action economy to do. And as it is adamantium, it is useful even after all of the charges have been used up.