User blog comment:Master Sima Yi/Assassinews 14-07-'14 – Two new Assassin's Creed: Unity trailers/@comment-5174994-20140731000622/@comment-1379990-20140801092125

That might explain the letters on his pocketwatch. If it's from his adoptive father and if it's indeed an 'e' (I had my doubts), then it would sense why those letters are on it as it was given possibly by his adoptive father. I read somewhere that it was indeed given by his father, but the page didn't specify which one (biological or adoptive). The latter would make sense, as someone already pointed out.