I agree with Clive's thoughts, but I am not so sure about it being a warding file.
I understand a warding file to be a slimmer version of a normal "flat file", usually double cut on both flat faces and single cut on both edges, and used by locksmiths and others needing narrow slots.
Rod
Edited By Rod Renshaw on 26/01/2022 17:42:13
Edited By Rod Renshaw on 26/01/2022 17:42:46