Psionic Energy is the resource pool

The number of dice is tied to proficiency bonus and the die size increases with Rogue level. The pool refreshes on a long rest, with the subclass also having a limited way to recover one die between long rests.

Psi-Bolstered Knack is failure insurance

When you fail a proficient ability check, you can roll a Psionic Energy Die and add it. The die is expended only if the new total succeeds, making the feature unusually resource-efficient.

Psychic Whispers is communication

The feature links the Soulknife telepathically with chosen creatures for a rolled duration. It is useful during scouting, infiltration and split-party coordination.

Psychic Blades are not a die expenditure

The weapons are manifested as part of attacks. The main blade uses a d6 damage die and the optional bonus-action blade uses a d4. Both deal psychic damage and use the subclass's weapon rules.

Soul Blades improve reliability and mobility

At 9th level, Psionic Energy can turn a near miss into a hit or become teleportation distance. This makes the same resource relevant to combat accuracy and movement.