I can admire a "beautiful" weapon
Pun intended?
Regarding the take lives to save more lives. Why can you use this argument for shooting people, but not for other circumstances. If it were universal, we would continue with human experiments to cure diseases and such, so that many more might live. But in that case we say, you can't weight one life with another and more lives are not worth more than one life. I fail to see the difference. Unless you say, some lives are worth more than others, but then it becomes difficult to quantify. After all killing people is just to further your own agenda, which in your eyes might be right, but in anothers might not be.
I think along the lines of what
@wichat was saying is, that you can take lives with weapons (or not if just used for sport) or hurt people with it, but if at all you can speculate that you might have saved lives indirectly. You can never save a life directly as you might do with medicine. (Ok if you are really picky you could say, you just fixed the tissue for example and the cells saved the body by growing back together, but you get the point.)
Regarding technical marvels. If you are really prosaically (is that the right word?) Most weapons are either made to plopp some material really fast out of another object into one direction, formed to sever organic tissues from another, or made to cause high pressures around themselves. The rest is romanticism and I feel there are much more impressive ends from other technologies. Even the means often seem crude to me compared to other technical marvels.