While the greek/english meaning of "nerve" is a negative one (i.e
"nerve" isn't a desired thing for someone to exhibit in his actions),

I don't know about Greek, but in English, this idiomatic sense of nerve is neutral, not negative. It's the context that colors it.

You've got some nerve showing your face around here again! (Negative)
He tried to work up the nerve to call her for a date. (Positive)

it seems that in the klingon way of thinking it *is* something
actually admired. So, I come across a situation described by the
irritating (for me) argument of "what a klingon would actually
do/say/think".

This is not a "what would a Klingon actually do/say/think" argument. This is a "what does this word connote" argument. There are definite cultural traits of Klingons that we are told about, some of which are generally admired by Klingons and some of which are generally disdained by them, and certain words refer to those traits.

I'm not exactly sure how everyone has decided that Klingons view qajunpaQ as necessarily positive. We're told it fairly clearly about butlh in TKW. But for qajunpaQ it seems to me to be pretty much an exact correspondence to the idiomatic sense of nerve, neutral without context. The only special connotation we're told about qajunpaQ is that it implies a surprising or reckless kind of courage that the neutral toDuj does not.

-- 
SuStel
http://trimboli.name