I'm afraid I don't know what valorous does on a weapon, but charging (in the MIC) is an enchantment that means a mounted charge attack with the weapon deals an extra 2d6 damage. Tripled for use of a lance with the mounted combatant feat is 6d6.
It feels big, but it's the tradeoff the weapon takes for being so specifically useful. Only when mounted, only on a successful charge; and building for charging, I'm forgoing the opportunity to use multiple attacks with a full attack actions (unless I can cheesilly get Lion's Charge from somewhere). Mounted charging is really Lamorak's golden situation!