KOS-MOS is a Rare Blade in Xenoblade Chronicles 2. She can grant tremendous power to her Drivers, Rex, Nia, Zeke or Mòrag, and their allies. She uses the power of light. She is armed with twin cannons. She is known as KOS-MOS Re: in the Japanese version.
KOS-MOS is a guest character based on KOS-MOS from the Xenosaga series. She is an armored android robot combat weapon with an artificial intelligence. Her design is based on the KOS-MOS's Version 1 model from Xenosaga Episode I: Der Wille zur Macht; both the original and redesign are by Kunihiko Tanaka. Her cannons' design resembles the Zohar.
- Lvl.1 - R-Blade - Puts enemies into a hornet's nest by spraying out bullets.
- Lvl.2 - H-Effect R - Develop the Hilbert Effect and change the course of battle.
- Lvl.3 - F-G-Shot - After charging energy, shoot out scattered laser beams.
- Lvl.4 - X-Buster - Fire a concentrated laser beam, but only when energy reserves are full.
- Recharge Boost - Boosts Arts recharge from auto-attack.
- Arts Plus - Boosts power of next Driver Art.
- Critical Up - Increases critical hit rate.
- Phase Transition Tech - Annuls enemy defense and increases Special damage dealt.
- Hyperclock - Deal more damage and take less damage at max affinity.
- Encephalon - Reduces aggro build-up from attacks.
- Light Mastery - Lvl. 3
- Lockpicking - Lvl. 3
- 'Mental Arithmetic - Lvl. 3 (Skill exclusive to KOS-MOS)
- Pouch item types: Staple Foods, Board Games
- Pouch items: Master's Curry (Staple Foods), Gladiator Wrestling (Board Games)
Some point after awakening her, she will start the quest Artificial Intelligence.