I played through
Super Castlevania IV tonight, and I found out something I never knew, despite beating it many times. In the end credits, it shows Simon swinging across a gap while throwing a knife.

So, as soon as the credits roll, I tried it with the boomerang in Stage 1, and it worked! For years, I've been doing careful dodges while swinging, especially in the clocktower stage where this unknown ability to attack while swinging would be very useful. Is this common knowledge? How many of you knew or didn't know this?