C78 Akainu Who Had Suffered a Setback in the Alabasta

Red Hair lifted Griffin's hand and waved to Lin Mo, oblivious to the Lava Dog rapidly closing in behind him.

As Red Hair drew nearer, Lin Mo noticed his left arm was drenched in blood, clearly indicating a serious injury.

It made sense why he was waving with his knife-wielding hand...

Lin Mo remembered that Red Hair had once lost an arm trying to save Luffy