that guy is obviously over geared.... (if you give kai the same gear, probably don't need as much def, you will see similar performance)
edit: and it's the fact that kai requires fewer gears to perform at the same level as other class, high dps and high survivability, that makes him op (yes, it's just like staffie, and that's why people say staffie is op too) You can use a overgeared sword fiona and compare it to a average geared kai and say that fiona performed much better; but that doesn't mean sword fiona is op, it's just the one you're talking about is geared to teeth, and makes her look like she's op.
Ask any spear lann with a +6 spear to solo klaus in 6 min without stacking def, not going to happen.
dps wise they are similar, probably spear lann will come on top if survivability isn't a problem; but spear lann requires def stacking to tank spin, and kai don't. Or you can say skills, but skill doesn't affect whether a class is op or not.
So basically he's good, but he does less DPS and it's cheaper.
Don't judge the whole population based on one guy -_-
Would you like me to link about 20 more? There's quite a few people doing stuff like this.
Characters like Evie only seem "too good" when they have average equipment, and "average" is a weird word at this point. Everyone will get scrolls from levelling up through the 60's that, even if they wasted their money, would at least afford a +8-10 and some basic armor. That doesn't include whatever other money/drops they may collect.
There was a time when it was a real pain in the butt to get started, but now that people are given a scroll that sells for 35-40m and a few more that sell for a bit less just by levelling, I think the standard for what is basic and average should be higher.