I don't think minor field repairs to the blade tip will void your warranty (not in practice anyway). I've seen much worse sent to Leatherman and they fixed/replaced it without a hassle.

Obvious, unreasonable abuse may be another matter -- such as burning the blades on a high-speed grinder and then demanding a replacement. They may well forgive you the first time, even though they're not obligated to.

I don't know if Leatherman tracks returns; they probably do. If you abuse tools outrageously, and constantly demand warranty service, you may get a less friendly reception over time. That's seems only fair (to me).