Hook: Floor Small (Green Square)The Rakata Warrior decoration fits into a small green square floor hook.
Hook: Floor Medium Narrow (Blue Rectangle)The Rakata Warrior decoration fits into a narrow blue medium rectangle floor hook.
Hook: Floor Medium (Blue Square)The Rakata Warrior decoration fits into a blue medium square floor hook.
How to Get a Rakata Warrior Decoration
Credit Decorations (previously crystal decorations)
The Rakata Warrior decoration can be easily bought for 50,000 Credits from a vendor on the fleet. It used to cost crystal commendations, but now can be bought with just credits.
To buy a Rakata Warrior decoration, head to the Crafting & Strongholds section of the fleet.
It is bound to legacy, so you can send it to your other characters... but once unlocked, all decorations are available in your stronhold legacy-wide, so the legacy-wide designation is mostly pointless. Unfortunately, due to the legacy restriction, it can not be donated to your guild's bank.