The flubbed line was "We can take whole by force what they propose to divide!" I've attempted to reconstruct it, but Okrand didn't remember the original line when I asked him. The problem is that the actor flubbed the line so badly that it sounds nothing like what was intended. The only clear part is the {pe'vIl wItlhaplaH} in the middle, which I'm pretty sure is correct because it fits the translation and is in any case clearly audible. There's a pause between {pe'vIl} and {wItlhaplaH}, which could mean that the actor dropped a word in between.
He does say something which sounds like "wawa" in the sentence, which is probably what you're remembering, which is likely the verb {wav} "divide".
The word {pe'vIl} appears in TKDA (the Appendix to The Klingon Dictionary). Many words in TKDA were invented for Star Trek VI, like {qo'} and {toy'wI''a'} from the same dialogue. TKDA also contains {naQ} "be full, whole, entire" and {lagh} "disassemble, take apart", which fit the translation of this line. (I wonder if {lagh} originated as a mispronounced {naQ} in a different take of this line?)
If anyone's interested to try to recover the original line, here's the scene (sorry I couldn't find a better version on YouTube, I have it on DVD myself):