I've been meaning to make a video about this for a while.
Here's what's going on:
There is a certain sweet spot you can sometimes hit when creating an armour spell in the corner. The breathing hitboxes of the game can cause Quan to instantly leave and re-enter the armour if you're stuck in between the corner and your armour spell.
When your armour spell is in the corner, you also will regain the armour instantly after getting back up from being knocked down. The corner gives you slightly different properties with armour than midscreen.
If your armour is in the right spot, you get armour back much faster because the game thinks you're leaving and re entering it. You also get armour back the second you stand up, making wakeup b3 super viable because it basically chews up anything the opponent tries to do. The opponent never expects you to do a wakeup button press as it isn't meant to work, but it does with the armour in the corner.
I'll make a video explaining it further when I can