BROKEN BLADE

Rygart Arrow is the only one in his world who lacks the inherent ability to power up quartz, the energy source that makes all of the machines run. Good thing the King and Queen of his country of Krisna happen to be old college friends! But so is Zess, the leader of the army of mechs invading Krisna. As usual, Arrow feels useless in the face of battle, until he comes across a powerful, ancient battle suit that no one else can run. His natural affinity for the suit's operating mechanism may just turn Arrow into the most important player of all. (Source: CMX) — Description from AniList community (anilist.co).