The red glare is not linked to flaming arrows; as I said before I turned them off and it made no difference at all. The glare is present whenever any unit that is being hit by arrows of any variety is on screen, even if it is hidden behind a hill or something. The screenshot doesn't do the effect justice; the red lights flicker and move like strobe lighting, they aren't stationary.

Updating the drivers is not really an option right now; newer drivers cause big lighting errors in thief 3. Thief relies on lighting, so it is unplayable with the glitches. I have to finish thief before I can update, and I am playing very slowly indeed because I'm busy writing assorted stuff.

Lorica segmentata on mounted units hundreds of years before it was invented