If a character simply has a flashlight on rare occasions (such as a cartoon character using one while going camping), it should not be indexed as an ability at all.
If a character has a flashlight as a regular and iconic part of their toolkit (such as Dead by Daylight survivors), it should be indexed as Minor Light Manipulation.
If a character has a flashlight, for any length of time, which interacts notably with their other supernatural properties (such as a character who can paralyze anything with a shadow, and once used an ordinary flashlight to facilitate that), it should be indexed as Minor Light Manipulation.
If a character has a flashlight, for any length of time, that has supernatural properties (such as sealing demons when other flashlights won't, or as being abnormally bright), it should be indexed as Light Manipulation.
EDIT: I also feel the need to point out that, regardless, this sort of thing should be indexed in standard/optional equipment. If there is some niche situation where it's needed in a fight, for a character made of darkness, one can simply point to that.