Here is the full list of all 18 Xenon Valkyrie achievements.
You left behind Thule Wulz Grotto
You left behind Acient Techforest
You shopped at the store.
You get an exemplary level
You left behind Prime Reactor
You left behind Ivory Tundra
You left behind Phoenix Wastes
You left behind Gilgacocoon
You raised the sword
You fought to the end
You got the legendary weapon
You Kill to Deftos
You Kill to AI MotherShip
You helped Dook
Fixed the Teleporters
You left behind Blackstorm Lab
You got his blessing
You got the best weapon