I quite like the idea of Polymorph being based on your constitution, at least partially. I don't think it's "too good of an attribute," but it is useful to everyone to some degree. I agree with Stabbey that there are too many int trees compared to dex and strength stuff.
Bard could maybe be based off of dexterity if playing instruments is involved, maybe perception as a sort of version of charisma (reading people, knowing what to say), or could depend on your investment in charisma even as another ability. Would need some powerful skills to require two ability trees to get full effect, though.
I kind of like merging trap master with lockpicking for a more general "devices" skill, unless they make lockpicking way more useful in D:OS 2.
