Given that it is a spear, it has quite a long reach to allow for some distance between the weilder and the opponent. All it takes is one hit and then I can gain the upper hand by rendering the opponent essentially powerless.
All thanks to the ability to change the size of whatever I hit with the spear. I can go from fighting a pissed of dragonslayer to having to deal with a dragonslayer the size of a lizard and be able to walk away the victor. Cheater move? Maybe a little but I'd have little problem fighting most enemies lol I could also play a support role within a guild and enlarge my companions to allow them greater strength and power from being the size of a dragon :)