Output limiter (出力リミッター Shutsuryoku rimittā), also known as Ability restriction (能力限定 Nōryoku gentei), is a method to ensure that a mage will not channel more magical energy than permitted, effectively reducing their mage rank by several levels. TSAB imposes power limiters upon its most potent mages when the latter have to work together within a comparatively small area, because magic of great magnitude endangers the fabric of the time-space. Removing a power limiter requires authorization by a high-ranked TSAB official and the release can be additionally limited to certain time.
Alternatively, limiters are imposed as means of protection, to prevent mages from overstraining and damaging their bodies with magic.
Devices have a functionality similar to power limiters, as their functions can be permanently locked and unlocked with sufficient authorization.
- Hayate Yagami, the commander of RF6, had a power limiter that reduced her level from SS to A. Only Carim Gracia of the Saint Church and Admiral Chrono Harlaown of the Dimensional Navy were authorized to remove it.
- Nanoha Takamachi, callsign StarS-1, had a power limiter that reduced her level from S+ to AA.
- Fate Testarossa, callsign Lightning-1, similarly had a limiter that reduced her rank from S+ to AA.
After the JS Incident, Lutecia Alpine has a powerful limiter placed upon her, presumably to prevent her from inadvertently using her extremely potent summoning magic. It is later on removed from her in ViVid during the training mock battle.