In ambush phase weapon disarming from the front at a close to point blank range weapon point threat status against any remotely capable and alert aggressor, never reach directly skyward above your head to seize and secure a weapon on instinct autopilot in relation to using only your sense of touch to locate and secure the weapon.
I can remember a lad on a course who told us of learning such weapon disarming on a traditional arts hybridized self-defence course. He was dismayed when it would not work against any CQC proponent.
The reality is when your aggressor is wired he will react to your most minuscule movement let alone a knee bend and vertically skyward reaching action.
Any enemy with combative capability and smarts will simply retract and use their weapon against you.