Hallowed Sword +20:
8001000E 44656661
756C7420 57656170
6F6E0000 00000000
1800000F 00000014
You'll kill any boss easily and quickly on both NG and NG+.
Note: you MUST have the sword as your active weapon before applying the cheat.
Update: you can get +30 as well by replacing the hex "14" (last line) for 1E, but if you try +99 or +1000 it won't work, the sword will be even weaker than before, idk why, just tested that today on the final boss. maybe +40 or +50 works too but I didn't test tough...
hope it helps you