We might also suppose that the reH remains before the main sentence but that latlh qabDaq modifies something else, and qul just gets in the way because of the odd syntax. It might be attached to tuj: fire's hot-on-another's-face is many, and all else's hot is few; this is always true. Or it might be attached to law': fire's hot is many on-another's-face, and all else's hot is few; this is always true.

 I would think of it as being applied to "A's Q is many", so something like "on someone else's face, fire's hot is many; everything (else)'s hot is few".

We also have {DujvamDaq tlhIngan nuH tu'lu'bogh pov law' Hoch pov puS} which follows a similar structure. "on this ship, Klingon weapons which are found's excellent is many; everything (else)'s excellent is few".