Clearly, just because I might be familiar with caltrops, and I know the difference between a flintlock and a wheellock, should I assume my readers are as well? While it might serve to aid simplicity by choosing another, more familiar object, it's also instructive to see how other writers have dealt with this issue. I raised this with a top-flight reference librarian, and received an answer today.
I present, therefore, a section of "One Corpse Too Many" by Ellis Peters, one of the Brother Cadfael mysteries:
"There's a herdsman's hut there in the piece where the track is in the woodland, though only along the edge, the fields still close. We were in this stretch when Nick's horse fell lame. I lit down to see, for he went very badly, and he had picked up a caltrop, and was cut to the bone."There you have it. I'm not sure how precise this explanation is, but you get the idea that it's unobtrusive, sharp and cripplingly dangerous. For my own story, I'll have to add in a bit more description than "razor-sharp caltrops", but not too much more. My thanks to the the reference librarian - the chocolate is on its way.
"Caltrops?" said Brother Cadfael, startled. "On such a forest path, away from any field of battle?" For those unobtrusive martial cruelties, made in such a shape as to be scattered under the hooves of cavalry, and leaving always one crippling spike upturned, surely had no part to play on a narrow forest ride.
"Caltrops," said Torold positively. "I don't speak simply from the wound, the thing was there embedded, I know, I wrenched it out."
Caltrops, by the way, are still used by modern armies for anti-vehicle applications (to puncture tires), and by guerrilla warfare groups to slow the advance of non-motorized ground troops. They'll go through the sole of a boot just as easily as into a horse's foot.
p.s. I sometimes use unusual words. I don't like to make my readers work for the punchline, but I'm not opposed to it, either.
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