This is extremely important, if you played the game as the other characters and are doing a final run a cleric, most weapons that scale with faith can't equip runes. I played through this last, played through thinking I'd mostly be upgrading faith, with vitality and endurance as a minor. Like you'd normally think of playing a faith character.
You can do this, I did, but it makes your character weak IMO. You're better off just using this character magic as solace, and make a strength build instead.
Shelter is pretty good because it means you don't need health potions, but it takes so darn long to do that I couldn't use it on most boss fights cause it would be interrupted before I could finish.
Now if you get to the end and need to put the final rune in your weapon to kill the boss with a faith weapon like I did, you need to do the final proving grounds. I'll put a video of where it is.
The weapon is called Stare, it scales with faith, and it has a weapon slot for the ruin.
Also if you've played through the game already and just want to get through the game as fast as possible, check out this speed run of the game.
It shows a few glitches that no longer work so you'll actually have to fight the bosses he either skips or glitch kills, but the rest works fine.
Final Proving grounds.