The hell! I just did realized, that i'm missing another 2 frames from the stairs animation too. I don't even know, how it's happened, but now it's should be much better. Also I have found the way how to implement the full animation cycle, so I'll post the results here very soon.
UPD:
[ Invalid YouTube link ]
Out of all fangames I've seen here, you managed to use the best stair climbing animation I've seen. Yet, there is something that NOBODY fixes in this animation: The constant speed.
Now, this is only a nitpick, and even the original Castlevanias had it, but the constant moving speed in the stair climbing movement REALLY throws me off. Specially in sprites that have such high detail like that.
Adventure Rebirth did it masterfully. Chris climbs one step, stops for a very brief period of time, and climbs the next. It's all very fast, but makes a huge difference. When the speed is constant like that, it doesn't really look like he's climbing the stair, but looks like he's "sliding while moving his legs" on it instead. It's like the speed of the legs doesn't match the steps they're stepping on. Here is how I believe it should animate:

But, man. This is nitpicking too much. Your game is looking good. Ignore me lol