Ena Launching provides Benisuzume and the other Garde-shaped Gaunas with range capability by shooting chunks of hardened ena like rockets.
Ena Launching seems to be exclusive to the Garde-shaped Gauna. Bensuizume can point her arm and fire peices of ena at high speed towards the target. This weapon is rarely used, but is deadly and accurate. The closest human equivelant is Anti-Gauna Missiles, as the Ena Rounds seem to be fired from under the arm.
While Gardes are amazingly maneuverable, Benisuzume seems able to easily hit and destroy them by Ena Launching.
Evading seems to be easy enough, but there is little opportunity to study the weapon as it is rarely used.
The ena projectiles seem to be pinched off and shot forward. Propulsion is never explained.