Historically, you shouldn't be able to find such a weapon in Viking Conquest. That way of using the lance started spreading in Britain a couple of centuries later, with the Norman invasion, maybe even a bit after - to be absolutely sure, I'd say XII century. After all, cavalry in the IX century was not as developed as it was during the native Warband XIII century.
I may be wrong quoting a later source from the Norman invasion, but if I recall correctly, that how cavalry probably used their lances/spear back then, over the head.