Please Help Me Understand Xin Zhao...

I know what his abilities do, but I never do...any damage at all. Seriously, I can't even clear minions, its single hit damage, each hit even in mid game only does like 1/3 damage, no matter how much damage I build I never do enough, and the abilities never seem to do any good when fighting. Sure, I can charge into someone, then I can q to attack and deal "bonus physical damage" which only ads up to a mere sliver, while someone else just bursts me down.

I always get out traded. I have no idea how in the world I'm supposed to play this champ. I've seen people go hard carry and destroy, even with a tank build, and even when I build full damage...I do absolutely nothing... ^^;