Does the Defensive Duelist feat work with Psychic Blades from the Soulknife Rogue subclass?

Question

I'm making a Soulknife Rogue and was wondering if the feat Defensive Duelist would work with the Psychic Blades or if I'd need a regular dagger to gain benefit from it.

Defensive Duelist:

When you are wielding a finesse weapon with which you are proficient and another creature hits you with a melee attack, you can use your reaction to add your proficiency bonus to your AC for that attack, potentially causing the attack to miss you.

Psychic Blade:

Also at 3rd level, You can manifest your psionic power as shimmering blades of psychic energy. Whenever you take the Attack action, you can manifest a psychic blade from your free hand and make the attack with that blade. This magic blade is a simple melee weapon with the finesse and thrown properties. It has a normal range of 60 feet and no long range, and on a hit, it deals psychic damage equal to 1d6 plus the ability modifier you used for the attack roll. The blade vanishes immediately after it hits or misses its target, and it leaves no mark on its target if it deals damage.

After you attack with the blade, you can make a melee or ranged weapon attack with a second psychic blade as a bonus action on the same turn, provided your other hand is free to create it. The damage die of this bonus attack is 1d4, instead of 1d6.

Answer 1

No, the Psychic Blade is not in your hand when it's not your turn

The important part of the rule is in your quotation, but here it is all by itself:

The blade vanishes immediately after it hits or misses its target[...].

This part of the rule means that the Psychic Blade only exists during your Attack action. After the action ends, your hand will be empty again.

This has other side-effects, like not being able to use the blade for opportunity attacks. It all boils down to the fact that the blade is only created by the Attack action, not any other situation that allows you to make an attack.

Now, it is pretty unfortunate for your subclass's signature feature being nerfed in various ways by RAW, so if you're going to be in an ongoing campaign with this character, I'd suggest that you ask the DM if they'd be willing to homebrew a few changes to the rules that let things synergize a little better. One simple change could be to say the blades can appear as part of any action you take on your turn (no specific action required) and that they disappear after being thrown (as in RAW) or dropped, or whenever you choose to dismiss them. It's possible that this will turn out to be overpowered somehow, but you and your DM will need to assess that for yourselves.