I see. In that case, I agree with you. I think he could easily have heard what it was from Hinjo, but knowing how to use it would probably require at least 1 skill rank of training. At least, if the DM were making logical rulings.
That's sort of an issue which applies anytime we set a maximum based on a strip which took place at least 1 in-comic day ago. Unless we are certain their level has not gone up since we gained evidence about some maximum, we can't really set any upper bounds.Moving back to Belkar's strength... we've got a problem.
In Snips, he doesn't have an 18 (max 17). We're not going to use that because it may have gone up.
But our proof for him not having an 19 (max 18) is here: http://www.giantitp.com/comics/oots0038.html
That was a *long* time ago.