Quoted from PinMonk:DO NOT continue buffing a faith character, go with your gut and abandon that path. You cannot finish the last boss with a faith character build. Giant game-end middle finger to players that chose that route with zero warning or clues along the way that I saw. I know they've changed stats on a lot of the bosses now with the last few patches, but pretty sure the final boss is still unbeatable with a faith-build character.
I only buffed Faith to 24 so I could try a few more incantations. I didn't plan going higher with it anyhow because I can already see there's no point in going further. I wasted my last 2 Dragon hearts on a ice blast when I should have got the rotting breath. It would have way been more useful for Radahn.
Rob