Why are you sold on piezo?

In my experience, piezo lighers die if the piezo elements get wet. Tough outdoor lighters may have some waterproofing in them to a degree to combat this, though, but that increases size/weight.

Flint lighers seem a lot more bullet-proof. If they get wet, flick them a few times until they spark. And if they fuel runs out, they may still be used to light dry tinder.