Of course it's similar to Animate Weapon, but they have different uses. Obviously the common mechanic they share is allowing for multiple weapons on the board.
Animate Weapon, although it allows for combos with things like buffing cards (and Crusader) and Twin Universe, fails to creature control (of which there is plenty), especially Reverse Time. Weapons in their normal form don't allow for these combos but also don't fall to CC.
Here's a huge way in which they are different: If a creature weapon is killed the opponent has just laid waste to two of your cards: the weapon and Animate Weapon. However, if a weapon in a weapon slot is destroyed the slot remains. So it can be reused.
Considering that, it may actually need a small cost increase.