Okay so I'm a level 16 rogue my skill build is Shadow Peircer 5/5, Aimed Shot 5/5, Razor shield upgrades 1 & 3, and SSS upgrade 3.

Question 1: Why do people use upgrade 3 on shadow peircer and nox? They do very low damage so why?

Q2: how do rogues hit high crits? I was in pvp and someone said they crit for something in 600's or 800's and then I find out this is "low". My pride isn't damaged at all knowing I've never crit over 500... does the bonus damage tell how much higher your crit will be over your normal attack? Or what?

I thought I had more than that but that is all I need for now.