Actually, green glass weapon traps, the discs at least, are wonderful for two, fairly niche, purposes. The first is chopping the hooves/feet off wandering wildlife, which a 10x green disc trap will do in pretty much one go. Whether you do it to collect hooves for crafting or to make the critters easier (No feet means crawling, yo'.) for your kill-squads to drop is up to you. Along those lines, they're also pretty good at getting critters to dodge (especially, I think, with low-quality mechanisms), which if you've got a drop beside or mostly surrounding the trap can be a delightful pastime.
The other is for room quality. A single 10x (less, actually, but green glass is free, so why not?) disc trap will make a 2x1 office opulent. More will make pretty much any room of any size ridiculously valuable in a minimum of space. If the aesthetics bother you, you can just set the thing up in one of the room's corners and hide it. Quite useful for that purpose, though.
Now, iron, steel, and bronze? Yeah. Those're deadly. My steel traps regularly chop unicorns and such in half with one or two swings. Good stuff, if a bit messy.
And the trap components (discs and spiked balls, especially) themselves are ridiculously valuable, so they make rockin' trade goods. Nice stuff all around.