Q:
Extra stats? and How to reach 500?
1. There are guides for that. But basicly you first discover exotics until lvl 450, then refine the new materials to 475 and the go back to discovering exotics.
2. You either get to a sufficiently high level in fractals and get lucky and drop that ring or you drop the uninfused one (or buy one from laurel vendor, WvW vendor or from fractals with pristine relics) and infuse it yourself.
Celestial stats are mostly considered to be useful on classes that use all stats like ele or guardian. I am not telling you not use these for you Warrior, it is yours. I’ll tell you, howerver, that similar things are available in other stat combos. The GS looks different though as its colors reflect the main stat.