Khazad-dum - Before the blackness, seek their doom.
H - The slender bough bears a unique gift, but what meaning does it hold?
Uzbad Khazaddumu - An elder claimed this eldest title, and sought the eldest's crown, but the eldest's servant ended him.
Zirak-Zigil - Here ended the endless; what did the makers make it?
Durin - Seven times named, but twice unnamed; what name is mine but never was?
U - A son full-grown bears his father's name in full.
Lahgaza [Agazhal] - Fall back, o masked one, and let the French striplings take the field.
[Theme: Khuzdul]
Yes and yes, and I'm going to take that as close enough to a theme guess to count. 'Durin' is the only outlier, standing in for a Khuzdul name we simply don't have; all of the others are directly tied to the language.
And I sincerely apologise for La Gaza.
hS