It was explained, but Mangapanda didn't translate it properly.
Basically, The Almighty has different levels to it:
- One Iris (in each eye). The "closed eyes" state, where Yhwach doesn't access his power.
- Two Irises. Yhwach gains omniscience - he can see and understand everything, even things which haven't happened yet. With that knowledge, abilities used against him are automatically countered.
- Three Irises. Yhwach gains omnipotence - he can not only see, understand, and counter abilities, but he also gains control over them.
Yhwach used Ichibe's own control over blackness to control the ink inside his stomach that he earlier swallowed, using it to explode his body. He may have also used Ichibe's control over names to bestow upon himself the name "Yhwach" again.