To get the White Glint AC parts, you must do the mission "DEFEND Line Ark." In the mission, White Glint is your ally and will disable one of your enemy AC's, shortly before being disabled by the other AC. You will then go 1-on-1 with Fragile (if you defeated him in the arena already, use the same tactic). After you kill Fragile and after the debriefing, you should get the White Glint AC parts.
