I still don't know if you can wield any melee weapon with this ability or not.
Can this be used to wield a longsword, even though it's not a weapon of the wizard? This is a question I would still like to be answered.
Also, My suggestion on regarding the hand is a feat giving it the ability to wield a two handed weapons and some other abilities that sound fun to me. Perhaps this would be better as a prestige class suggestion but I thought it was neat so I figured to share. While I'm not sure if it can wield a longsword, I'm guessing it cannot wield a two handed weapon.
Hand of the Adept
Your hand of the apprentice becomes strong enough to lift bigger weapons.
Prerequisites: Hand of the apprentice ability, 13 Intelligence
Benefit: You are now able to wield a two-handed weapon with your hand of the apprentice ability.
Hand of the Mage:
You have learned to channel touch spells through your hand of the apprentice ability.
Prerequisites: Hand of the apprentice ability, Base attack bonus +3, 15 intelligence
Benefit:As a full round action, you can deliver a touch spell of 3rd level or less through a successful attack with your hand of the apprentice ability.
Hand of the Wizard
Your ability to control your hand of the apprentice has become second nature.
Prerequisites:Hand of the apprentice ability, Base attack bonus +5, 17 intelligence
Benefit: You can concentrate on your hand of the apprentice ability in place of a move action instead of a standard action.
Hand of the Arch-mage:
Your ability to channel magic through your hand of the apprentice ability has been mastered.
Prerequisites:Hand of the apprentice ability, base attack bonus +7, 19 intelligence
Benefit:As a full round action, you can deliver a touch spell of 6th level or less through a successful attack with your hand of the apprentice ability.
Anyway you get the point... you could have a feat where it threatened AoEs, allow a full attack action, or really a number of effects. This might be better as a prestige class ability but I thought the idea was solid.