I was going to try to build something off his childhood friend, but she apparently fell down stairs??????? and that's too absurd to work with!!!

Infrequently, once or twice or thrice a day — as often as you like, if at all, for the number of days you prefer — Zoro finds that, when he takes up his own sword, he briefly... can't use it. Perhaps his hand is numb, his grip too tight. Perhaps he freezes, for some reason no longer recalling any of his combat moves. Maybe fear or existential dread strike him. He is fleetingly useless as a swordsman during those moments, until he sets down his sword and tries again. Note: this 'skill paralysis' never happens when he tries to use any other sword and is exclusive to Wado Ichimonji.

The effect can dispel whenever you want it to, but should last no longer than the remaining duration of the Ephes Arc!