Some ideas i liked:
Mages making mana
Giving Priest Sprint skill
How about an archery skill that drains mana and does damage . (Obviously not spammable)
I don't see the harm of adding a cure skill for mages/warriors if it has like a 2minute cool down. It'll make solo pk on these classes just a tad bit easier.
Some tampering with warrior's passion skills would be interesting too...