chuvmey
Talking with Marc Okrand it's difficult to stay focused on a narrow point of grammar, 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 imagine.
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.