Kyoraku's bankai seems to end with an auto-cut across the throat... which I do not believe would cause a scratch.
Iirc, the example he gave was crossing out the name of someone's 'arm' would cut it's power in half.
He also wrote 'black ant' on him to give him the power of an ant, but that needed more writing and didn't even work. That's the one that reduces someone's power below half, I think.
He did remove the name of the enemy's sword, but I think that just prevented the use of sword-related powers since in Bleach names are needed for that....
Ichibei definitely has the best shot of anyone, but too much writing is required, and I'm not sure how far down he can really reduce someone's power.