Ki-awase means "blending with your partners ki".
Technically the attack is a forward strike to the head with tegatana, beginning from chudan position.
Seems there are at least two common possible scenarios for shomen-uchi. One where nage waits for uke to initiate shomen-uchi
Or the old form, where nage initiates a technique using shomen-uchii, in this case sometimes like a simple sliding forward movement to the forehead., but at the same time as if deflecting the tip of ukes sword ( ukes tegatana).