I have no images nor videos for this, but basically Fillmore repaired my items when I entered his “sell” window. The first time it happened was when I first encountered him, and I thought maybe it automatically repaired everything because I rescued him.
Then it happened a second time, so the third time I checked what action triggered this and it was selecting the sell option. Clicking on it just straight up repaired all my damaged equipment.
Sadly the fourth time i checked he had already moved near the first boss arena, and this stopped happening since.
Here are the requested files: