I'm a ninja in the storm server who is too lazy to level up, so I stay in the arena and win 2 exp balls daily, if you are a ninja here are some good tips to win against other classes:

Taos - this is the hardest class because you have very low defense, if they hit you 1 they will surrender most of the time, but if not, keep your distance a bit and when there are 2 seconds left to start jump and twofold blade them.

Archers - if you have a good armor they will normally hit you one, if they use fly stand beside them, use archer bane and twofold blade them when they get down, they will be unable to move for about 0.5 secs, so use them good. If they hit you 100 or more and they are flying all over around, then you will most likely lose XD.

Trojans - don't be intimidated for flashy armors and super weapons, ninjas are the class with most attack, so you will hit good. Just beware for Hercules, so jump into them and stop right out of range then immediately jump again into them and kill them. Fogging is a very good option because they have a lot of hp and stack a lot of points.

Warriors - the easiest class to beat, if they use swords or blades just don't jump straight into them. Of they use wands jump around and twofold blade.

Ninjas - Check their equipment fast if you think you ban 1 hit kill him stand beside him and twofoldbalde as fast as you can, if they easily kill you and they stand beside you, you can either take a chance and in the last second jump behind him and kill him, this works a few times only, or you can move around fog I'm and hit him when you have a chance. If he stays away before it starts he will probably fog you so stay away.

A final tip, if you are sitting getting stamina and the other guy comes; when he right before his jumps jump away and fog the spot you were, by the time fog hits he will be there.