I am Mezana Porta di Ferro, Dopia e Incrosada (Middle Iron Gate and I am doubled and crossed). And I am good in armour, but not without because I cannot make long covers. And I can cover above and below with the right hand and the left hand with the dagger or without.
Although shown defending against a sottano attack here, this posta is used by the Seventh Master defending against a fendente attack. As stated, he can cover in all directions. The blade of the dagger extends down the right forearm, and the left hand holds the blade with the thumb at the tip.
This defence uses a ‘sticky hands’ principle, where the dagger is firmly braced to make a strong cover. You can then roll your left hand onto the wrist of the attacker, controlling their weapon, and freeing your own dagger to make a counterstrike.
Due to the mechanics involved, the arms need to be held close to the body, leaving only a small margin of error in completely avoiding the attaking dagger tip. Because of this, it is not a good technique to use without armour.