I used {-na'} because in my mind, I had attributed to it the meaning
"to be real, true" as opposed to "counterfeit". In other words,
somewhere along the way, I started perceiving the {-na'} to be
conveying a meaning opposite to the verb {ngeb}.
Luckily though, yesterday, I had the idea of checking with the tkd.
So, lets remember, the way {-na'} is defined:
tkd:
> {-na'} <definite>
> This is the counterpart of {-Hey.} It indicates that there is no
> doubt in the speaker's mind as to the accuracy of his or her
> choice of words. Once the Klingon officer referred to above is
> sure that the object the scanner has found is a vessel, he might
> report the presence of {Dujna'} <a definite vessel, undoubtedly a
> vessel.>
So, after reading the relevant tkd part, I understood that by saying
{tamghayna' 'oH Hurghchu'ghach'e'}, I'm not actually saying "perfect
darkness is the true light" (true as opposed to fake/counterfeit).
By saying {tamghayna' 'oH Hurghchu'ghach'e'}, i'm actually saying
"perfect darkness is the definite light" as in "perfect darkness is
surely the light".
You're missing something fundamental. A verb used adjectivally describes something about *the noun* it follows. The suffix {-na'} indicates the degree of *your* (the speaker's) certainty about it. {Dujna'} is not "a vessel that is definite", it is "a thing that the speaker is sure is definitely a vessel". {teH} and {-na'} are not even comparable, because they apply to different things.
A {ngeblaw'bogh Dujna'} is a thing which the speaker is sure is a ship (as opposed to, say, a missile), but which he or she thinks may be fake (i.e., definitely a ship, but a fake ship as opposed to a real ship).