Part of it is that first person animations are downright impossible to change in Creation Engine. Of you want to see third person animations in first person, use Immersive First Person View from the Nexus. Skyrim is made in a poop engine. A lot of the things modders wish they could do can't be done because of the limitations. Spears by Soolie is a great mod and you have to remember spears were also used in slashing motions, as the tips were able to slash and stab. Yes the animation is vanilla, but consider this; if you were to change the one handed swing for spears, it would change the one handed swing for swords, daggers, war axes, and maces as well.