A lance is a weapon that injures by penetration, so a dream that you are attacking someone with a lance can be a message that you need to cut to the heart of an issue, even if doing so may cause someone pain.
If you dream that someone attacks you with a lance, your dream could be a warning that someone in waking life is getting through your defenses and may attack you where you are most vulnerable.
This dream could be telling you to be more careful about letting down your guard. On the other hand, your dream could be telling you that you need to allow yourself to be willing to open up to other people.
A lance in a dream can represent a need to cut something negative out of your life.
If you dream that you are lancing a boil, your unconscious is telling you there is something toxic in your life that needs to be removed.
A lance in a dream can symbolize masculine power and masculine sexuality.