Levius est Vol 1

Levius est Vol 1 by Haruhisa Nakata. A Sci-Fi manga rated Older Teen, published in English by Viz Media in 2019.

In an alternate world of steam and machinery, young Levius lost his father and his arm in a war. Now fitted with a mechanical limb, he fights in the brutal sport of mechanical martial arts, where every bout could be his last.