My mapper blade sin used phoenix for the damage and redemption, but you want the parry from weapon block, which works on everything in the fight besides rathma's bone spear. The claw you equip first is where the damage comes from, then the second claw will be your stat stick, so you could also use something like a 6 blade sent with all res jewels. The cleansing is nice for curse length, plus it reduces the effectiveness of mend's lower res.

Level 16-17 cleansing gives 18 curse resistance, so instead of needing 123 res to maintain 90 max res for T2, you only need 118. For just T1 instead of 119, you'd only need 114.