85 Arm Strength backed by Blade of Muramasa only does 1 to 2 damage -- No better than just punching the thing. By the time I finish, I have 97 Arm Strength. The only better weapon to find is in that small chamber right after the boss. Don't bother magicking the boss, it's immune.
In any case, I only did minor-medium luck manipulation. Enough to delay some of its attacks. I did not deal with the 1-2 damage jitter. It has 250 HP to knock down. I should check if cheating my strength to 99 has any effect, other than muting the Arm Strength messages. Would let me know if I should keep the Blade unbroken until my arms grow a bit.
On a side note, I'm really, really glad frame perfection alone is enough to survive those arrow traps... 100+ damage doesn't help someone who only has 44 HP.