Hi so, don't be alarmed but this is me giving advice and a small critique on your character.
A Sangheili assassin, while not unheard of, is rare among their race as such individuals were viewed with a certain level of contempt and having little honor, so I'm not sure how well your character who had been a career soldier, albeit a spec ops soldier, would make the transition to an assassin.
Plus the bit about the Unggoy (Grunts) will need some elaboration on, since as I understand it the only fighting done by Sangheili against the Grunts was during the Unggoy rebellion in 2462, a full 63 years before the Human-Covenant war.