The knight sounds like a push-over, only 5 damage?
That's 20 hits with a sword, that's pretty bad. I'd bump it up to like 15 and thrust maybe 35, but 5?
No wonder everyone would be playing as the Mage.
EDIT:
Wow, just reading the bottom about people have 4600 HP, that's ridiculous.
Do the math.
4600÷5=920... 920 hits with a sword to kill someone?
That would take like 5 minutes, and think if they were a ranger or mage, they'd be so far away you would have no change.
I like the ideas of everything else except the extremely underpowered Knights.
Unless he has a whole load of HP at first though.
SECOND EDIT:
Ok, I just read the damage scaling thing, but even at level 1 it's weak. Unless knights scale really fast.