Sheath working incorrectly

[Hahaha 51]

Hey guys, 

So recently I rigged the classic Goblin model onto the Cata animations, and everything basically works perfectly except for one massive glaring flaw: the weapon won't unsheath correctly. So, for example, when the Goblin attacks, he attacks with the 1h dagger animation, but the dagger is still on his hip. However, when he casts a spell, the dagger attaches to his hand and won't leave, even if sheathed. Does anyone have any pointers into what I should be looking at to fix this?

Thanks in advance.