I feel like "battle junkie" is a more commonly used and... elegant?... phrase than battle loving blockhead, but maybe the author used a different phrase that specifies him being braindead? Would idiotic/braindead battle junkie fit better?
man this is one of the few mangas where i love the fuck out of the MC and FMC, like usually one of them is more enjoyable than the other, but these 2, they work so well together