en_tn_condensed/rev/19/12.md

His eyes are like a fiery flame

John speaks of the rider's eyes as if they shone like a flame of fire. (See: rc://en/ta/man/translate/figs-simile)

He has a name written on him

You can state this in active form. Alternate translation: "Someone has written a name on him" (See: rc://en/ta/man/translate/figs-activepassive)

on him that no one knows but himself

"on him, and only he knows the meaning of that name" (See: rc://en/ta/man/translate/figs-rpronouns)