Wdym without the eye?
He killed his brothers without the eye of Natam.
Unlike his bro's, Shu was born with the eye of Natam. It's that thing on his forehead
Same as Nashid and Jakar.
You might wanna reread.. Shuraka already had the eye of Natam from the moment he was born (unlike all of his brothers who got it only after the first time they spread their seed). So he killed his brothers with/already having it, not without it.
Ican't wait to see Shuraka's POV and how he managed to kill his father and all his brothers without the eye, plus the thoughts he had for his beloved.