I'm assuming that once these thing have a greater usefulness (maybe a low skill makes it pretty useless). I was thinking that this might make fighting a tad bit more interesting...
Dodge: this is fine (assuming it's useful at higher levels or after combat is fixed).
Parry: How about when a player attacks with their left mouse against a player attacking with their right mouse, then THIS is a parry. It's not the same, but it's kind of what you see on sword fights. Both fighters swing their weapons at each other and end up connecting whether a block was intended or not. This will mitigate damage quite a bit and make the use of left and right mouse attacks more useful. Both fighters will also have that parried side "stunned" for something like 0.2 seconds. So you can attack right after with the other hand if you wanted, but not with the same hand.
Block: The current parry, but you can hold this down. You move slower, but not as slow as stealth and you can't run or jump. It drains stamina and some health when attacked. You lose more stamina then if you attacked normally. The attacker will not lose hp, but will be stunned for like 0.1 seconds.
What does the people think about this?
It's an idea btw. I thought about this in 3 minutes. Flame if you want.