You may wish to look for a Museum of London publication by Cowgill, J., et.al. entitled
Medieval Finds from Excavations in London:1 Knives and Scabbards. London, Her Majesty's Stationary Office, 1987. There are three pages (21 - 24) of illustrations of maker's marks, though I do not see any exact match for yours. A number of knives are also illustrated and your blade does appear to fit the overall pattern expected from a medieval knife.
As to conservation, please refer to
this previous thread, specifically Matchlock's advice.