I believe it is set like this on purpose (maybe you could use the two-hand animation if you wanted to?) Here's the code in attack.cpp: 
	Code:
	case ItemType2HBlunt: // 2H Blunt
{
    skillinuse = Skill2HBlunt;
    type = anim2HSlashing; //anim2HWeapon
    break;
}
 
	Code:
	case Skill2HBlunt: // 2H Blunt
{
    type = anim2HSlashing; //anim2HWeapon
    break;
}