Vampire Killer as a name for the whip didn't appear until Bloodlines, IIRC. So the Morning Star is the basic equivalent for SImon's Quest. This also explains why the nature of the whip itself changes so dramatically from Castlevania 1 to Rondo (which also came out before Bloodlines!). I always assumed that the handle was the necessary part of the VK, and the actual whip on the end was modular. Makes sense, especially if it's leather - leather degrades over time.