If you're a spellcaster, sure, just for the stacking bonus to spell save DC and spell attack rolls. But then it's better to compare it against a magic staff, not a shortsword...

For actually stabbing people, I think Knife of the Undermountain King is better.

I dunno, who told you Rhapsody is better and what was their explanation when you asked them how?

Better, for specific situations.

The attack and spell save DC bump at 3 is really damn solid for casters in specific. Pair it with some acuity, and hello guaranteed control spells.

As a weapon used by a melee fighter? Not at all.