Wow. That was special, in a short bus kind of way.
If at first you don't succeed, try, try again.
Move to stow lance. Horse moves to I-21/J-20. Free to shift greatsword to 2-handed grip.
(1d20+10)[29]
(2d6+6)[11]
Might as well attack with the horse too, for what it's worth.
(1d20+1)[9]
(1d6-1)[4]
Boosh!