Shouldn't that be <bIwejpuH>?

I think I understood this sentence in a different way. {wejpuH} cannot used as a verb, as it's an exclamation. Due to the comma in the English version, I perhaps understood it as "Charming! You are (indeed), my dear." Perhaps I accidently treated {wejpuH} as an adverb.

But it seems the English phrase simply means "You are charming, my dear.", so {wejpuH} doesn't really fit, as it's only used ironically...
Hmm... makes the sentence difficult to translate. Any better idea? Something along {bI___ SoH, bang.} would probably fit.

Ah, right; I was under the impression that <wejpuH> was technically a verb, even if it was never used as one. Looking at it now, however, it seems you're right.

I'm actually not certain if the sentence is to be taken ironically or not; I can read it both ways.
If it is ironic, however, I think simply <wejpuH bang.> would be preferable.

If not ironic, I guess something like <bIQutHa'> ("you're unvulgar") would work, or perhaps <bIbelmoH> ("you please") or <bIDochHa'> ("you're unrude").

One might also add a -taH; depends on how one reads the English sentence.