Victorinox
The Fine Screwdriver is a small 2.5mm (approx.) straight/flat screwdriver located on the backside of some larger Victorinox models, usually 'behind' (ie in the same layer) as the metal or wood saws.
The image shows both the current (top) and the original (1973-1985) version of the tool (bottom).
The width of the blade may have changed over time as well.