Carth IS a Mandalorian Wars veteran, but he was also famed as a pilot and less as an "on-foot" fighter, and he has no real feats or accolades in the latter capacity that I can recall. Presumably he can kill small numbers of thugs or Sith Troopers with his blasters, but I think Beckett could replicate those feats easily enough. He also had a good quick-draw. Enfys Nest was too much for him, but that's a feat for her I'd say. In all, I'm honestly inclined to favor Beckett.