Been watching these clips and reading these remarks....
Look at a pro third baseman. As the batter swings, he is prepared to:
Catch a pop-up
Catch a line-drive
to the right
to the left
to his center
Catch a ground ball
to his right
to his left
to his center
(already Hick of Hick's Law is lost. If Hick was right, the third baseman couldn't even move as he would have to select from some 8 tactics in an instant)
All at the crack of a bat, he knows what's coming, but doesn't know exactly.
An knife attack comes
1) in a committed lunge that lingers
2) in a hit and retract, (pumping, stitching, etc)
3) 1 and 2 in a thrust motion
4) 1 and 2 in a hook motion
So, there is no one solution. What works for one, wont work for the other. The competent defender has to be free to "catch all the balls" that come his way. Loose, free. Capable.
In that sorry aikido stab clip, the stab is coming in, in a committed lunge, straight-line (not the more common upper cut.) That committed, "giving" lunge gives Mr Energy the ability to do his aiki trick. (one I would not try, as there are faster, more brutal strikes that amp up the success rate.)
Be the third baseman, at the "tip of the spear" so to speak, ready to respond to the list of attacks. Lunge, stitch in a thrust or hook.
Basic Training. The attacker
Thrusting stabs on the combat clock
Hooking stabs on the combat clock
Hooking slashes on the combat clock
- Practice dodging and evading
- Practice using stuff around as a shied of weapon
- Clear knife attack (block, deflect) while...
- Hitting the eyes (or throat - hit what ya got best)
- Wrap arm if you can
- Kick and beat the high, holy shit out of the guy
Start by practicing that. It's just 4 groups of things!

Hock