punchy - 1: having an immediate impact; forceful: his style is journalistic, with short punchy sentences.
2: another term for PUNCH-DRUNK.
punch-drunk - stupefied by or as if by a series of heavy blows.
punchy - (inf) a: (sentence, speech, etc) schwungvoll (inf) b: (Boxing) benommen; (fig: = confused) benommen, durcheinander (fig)
You're right that this sense is missing from LEO, but this is the wrong section of the forum for that, since the existing entries aren't wrong. Next time, if you don't find the sense you need, just ask for a translation in Deutsch Gesucht, or if you know the answer, suggest it in New Entry.
Still, now that the thread is here, I would certainly support adding a translation for this sense of the word, if German speakers can agree on a few. To me, although it comes from punch-drunk, it's no longer quite the same as dazed in a neutrally descriptive sense, but often more humorous, self-deprecating. It's typically used in the sense of no longer making sense, wandering from the topic, growing silly, no longer caring, etc. Losing one's grip on logic or rationality, maybe, much like 'losing it.'