Talking with Marc Okrand it's difficult to stay focused on a narrow point
of grammal; other bits and pieces of tlhIngan Hol lore crept in here and
there during an hour long chat, snippets which didn't quite lend themselves
to the interview on -ghach, as definitive a case of leftovers as one could

Those mystery words from PK can be revealed at last. mate with is
ngagh, and get off is actually lItHa'

And finally, somewhat back on the target: the origin of -ghach. It all stems
from poor Worf's fate, his decision to take on the discommendation. Having
the verb naD making naDHa' was simple enough, but what to do for a
nominal form? Enter the ever-popular -ghach! But we can't blame Worf, or
even his father, for as we all know Mogh was not a traitor. If you want to
blame -ghach on someone, blame the house of Duras.