Given the intricacy of the smithing that seems less than sensible, it's not like the size of the items changes significantly, so having markings you can just wipe away and needing to re-measure and re-mark the item regularly sounds far from optimal.

> having markings you can just wipe away and needing to re-measure and re-mark the item regularly sounds far from optimal.

Unless the delibility of ink was a feature they desired. Hypothesizing that they were trying to prevent a working ranger from falling into the wrong hands wouldn't strike me as absurd. Dropping them in a firepit or stream to remove the ink would be pretty handy if you know your military encampment is about to be over-run and you can't save everything.