Vin-Tak fought Lady Sif equally in combat and defeated her after erasing her memories.
(The effects of erasing someone's memories doesn't affect the person physically, since Vin-Tak remained conscious after his memories were erased.)
Later, Hive (having a Hive mind and can see the memories of everyone infected by him) told Daisy (infected by Hive) that the Kree Reapers where stronger than the Krees they had faced until now. (Vin-Tak was the only Kree they fought. Mockingbird who has shown to overpower May couldn't defeat Vin-Tak but stall him. Vin-Tak also defeated Mack with one punch and Hunter too.)
The biggest proof that KS is soul manipulation is mayuri. mayuri can easily replace all parts of his body if KS attacked the body (as people love to say) KS was supposed to be immediately canceled as soon as mayuri replaced his entire body.