Hachi is basically just a bowl or pot and Wari is to crack. Typically the word applies to pots used for plants but here it is about whacking someone on the head. Hachi can also refer to the crown of the head in other words.
We did the Kihon and the Henka at the same time. The Uke is in Seigan and the Tori is in Morote Dai Jodan. In one leap (to the opponent's left) you close the distance and end with the Daito on the head and the Shoto on either the sword (or ideally on Kote). The Henka goes to the left but requires a bigger move to end up with the Shoto anywhere near the head.
"Make sure you use both stances (left leg forward/right leg forward) and practice moving off either foot in either direction."
The second round of this training the Uke resisted, either parrying the initial cut, moving back or attacking (Kihon movement) in response to the attack.
The Keiko no Ho was against all other Kamae including Kyoei no Kamae.
"The Uke can resist in any way, move back cut or whatever. Please develop your own Kufu to respond."