Is it worth it to save all those souls of a X and large souls of a X, or should I use them immediately to level up?

another question: how the fuck do I get past these things throwing spears at me in anor londo, I can't even see where the spears aare coming from and they just keep knocking me off of the buildings

if someone can help with this it'd be really nice because I feel really stuck and unable to progress, and I can't level up to improve things because it's not the damage of the spears that kills me, it's falling, they push me off even with a shield up

@Felthry if I remember correctly, the spear throwers are up on a tall building beside where you are...