Responses
Remember he was with his team at the time and was the last one left so the others could escape. I think they simply ran out of anything useful in their gear. He must have been quite tired and that's why, as he said, "he didn't notice one" that inflicted such a serious wound that he died within a few minutes. While this is just my guess, I hope it explains a bit more why he died despite being a veteran.
There is something really unique about this one I can't exactly explain, but the one issue for me is how easily he died. He said he himself could be considered a senior explorer, and has killed so many monsters that he was no longer sick of the smell of their blood. Naturally that would mean he has an inherent prowess in combat either through talent alone, experience, and both, yet when he takes a deep wound to the chest, instead of using any sort of first aid supplies that one would NATURALLY bring in this situation, he just monologues for a while before bleeding to death. I have no idea how this man survived this long.
Bit of a nitpick but whatever, I look forward to reading this whole series