If you press X while your horse is at or near max speed however, your character will adopt a jousting stance and the weapon icon in the lower right corner will show your polearm angled horizontally instead of pointed up. If you're like me you probably largely ignored the different modes and continued charging past on your horse hoping for a lucky left click thrust on their head.

So for those that don't know, many of the polearms (not all) in the game have the alternate usage mode 'Couching'. This might be old news to players from the first game, but this is my first experience with Mount and Blade, and while I'm loving the experience so far I am constantly finding mechanics that were never really explained that absolutely change the game.