make the light lance  1 slot non sheathable.  Less on horse fighting power,  more off horse fighting power for polearm users,  making it actually an interesting choice.
i still wouldnt use it,  but for all the non cav guys who keep whining about lance balance,  there you go.
older thought would be a higher lancing angle for shorter lances,  but iirc,  that isnt possible without changing all lances angles.