yes, you can use a coated knife on a firesteel, as soon as the coating wears off a bit. the corners on my rat three aren't particularly sharp, so they don't make a really massive amount of sparks.
the coating is very easily removed with a chemical paint stripper, i used nitromors. the finish underneath wasn't nearly as bad as some i've seen.
D2 does make a wonderful small blade for cutting. I just wouldn't want to take another chance on chopping with one, especially if my life depended on keeping that knife.
yep, some folks can get a little over excited when talking blade steels and stuff. it might be worth pointing out that the rat three is indeed a "wonderful small blade", about a three and a half inch drop point blade, with a full flat grind from 1/8" stock. so not really a chopper. though it's quite tall (edge to spine) for such a small knife, so it's really easy to use with a baton, mine gets used with a baton quite alot.
i rarely carry a knife on the belt when i'm out and about, so i really like the compactness of the rat3 with a little kydex sheath. i have the sheath tethered to my belt with a short lanyard. all i have to do is pull the knife out of my pocket and push the sheath off with my thumb, or the sheath runs out of cord and pulls straight off the knife. ideal way of having a fixed blade discretely to hand without being a pain in the neck
here's the D2 version:
cheers, and.