I've had a few Mantis knives, a couple yrs ago. I don't know if they now actually use the steel advertised, but I recall some respected members (I believe STR being one) that questioned &/or tested some of their "better" steels & their HRC were not what was advertised. That brings into question of whether the "nicer" blade steels are really used. This one, however, is advertised as having 400 series stainless steel, so it's not even 440A.
Having said that, Mantis seems to have found a "niche' where they offer designs that aren't, shall be say, terribly practical.
I don't think the design was necessarily meant for killing as you mention, but just something different. They seem to have a model with single edge & double edge, probably for those that can & those that can't legally have them. It doesn't appear to be terribly good at either function that it seems designed for (Bottle opener/knife), but I guess some will find it useful.
This knife's also not real expensive, although it's not "that" cheap either. It's advertised as a G&G Hawk collaboration knife. I'm guessing it's a design other knife manufacturers weren't really interested in. It kind of looks like a gaudy version of Kershaw's ET.