The kid epsilon was talking to, I forgot his name, has no arm??

I don’t remember if we actually know that part. He may have gotten injured, or was born that way.

It’s not plot relevant. Could be born that way, could be something else, doesn’t matter. His character arc is about living with his disability and continuing to be optimistic, smart, driven, empathetic and selfless. He serves as another example of how people dealt worse cards can rise above their situation; the good of humanity. Sys is another example of this.