So, if you need the bonefire you only have 2 solutions, 3 maybe.
-You unlock the elevator from Sen's fortress, it requires a key and every time you want to reach Anor Londo you need to watch the cutscene, definitely not the best option.
-At the lowest stage of the twisting elevator there is the darkmoon chamber with a bonefire, that is a good compromise but you have to activate the elevator every time, not so much time efficient but the best option.
-If you have the Archives unlocked the way from the first bonefire to Anor Londo is still viable, but at that point why do you even need to return there?
If you want to make the knight non-hostile you could've used the pardoner at the Gargoyle belfry, unless you really pissed her off for lore reason that I won't explain.
If the knight is dead...You can't do anything to revert the situation.
