Bar Mace has 2 more blunt damage on swings but has no thrust attack (which can be useful, I've already explained how). A little bit more length is nothing. You're hardly gonna feel that one point in battle.
Most importantly, Bar Mace looks like shit imho. Long Iron Mace is one of the better looking weapons in this game (also imho). It's a shame it can't be used on horseback anymore.
If you want a proper buff, this is what I propose. Make it slower, like 90 speed, lower its damage by one point (32) but make it usable on horse again. Also set a new price for it, let's say 9.5k gold. This way it would become epic 2H cav weapon, which seems logical (to me it looks more like a cav weapon).