You could do it the other way around, though: attack with the Psychic Blade using your Attack action, then with a short sword using your bonus action from Two-Weapon Fighting, but you'd need the Dual Wielder Feat, since Psychic Blades aren't light.Ī multiclassed Soulknife with access to Extra Attack could use a Psychic Blade as one of their primary attacks (i.e. It only manifests if/when you're using it as part of the Attack action. It does not say you can manifest a blade and use it for whatever purposes you want, so it won't stay in your hand while you perform an attack with another weapon. Psychic Blades says that when you take the Attack action, you can manifest the blade and make the attack with it, meaning the attack you get from the Attack action. Regarding using it as the bonus attack from Two-Weapon Fighting, you can't.
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You master fighting with two weapons, gaining the following benefits: Don't want to be a nuisance, but I don't see the +2 damage in the Duel weilding feat.