Really? Huh...as a player I would feel kind of disappointed to have the same item show up in two consecutive campaigns.Or are you starting fresh and your player who got the sun blade last time would be a little put off to basically get the same weapon again?
-This makes the least sense to me, since it implies Hypothetical Bob is playing the same character, or a similar enough character again.
Why is why they never should have put it in OotA.-And frankly, The Sunsword had some serious restrictions on who could use it (don't know if CoS removed these). It was entirely possible to run a Ravenloft campaign back in the day and nobody could actually wield the thing.
It is THE Sunsword, not a sun sword. The original you might say. Often imitated, never duplicated.
The Sunsword itself was not a particularly WOW! weapon, pretty much ever. It's setting implications were what mattered since it was basically the only thing capable of destroying Strahd for good. I would suggest to the OP to look into ways to pump up the flavor factor of the weapon. It's less what it does and more what it symbolizes in a setting like Ravenloft.