Your character's spear sweep isn't actually possible, at least not the way you've written it. Sigurd is three feet away, the handle is two feet long, unless Iolanthe is literally holding her arm fully extended downwards there is no way the foot of steel past the handle can be under Sigurd's shield menacing his feet unless the five foot of steel behind it were actually plunged into the ground. -Unless- she is holding the spear behind her body, in which case I really don't think it would be possible to generate any power in a sweep. 

Regardless, I highly doubt a sweep of this kind would be possible with human strength, and if it were it definitely wouldn't be cutting straight through leather boots and severing tendons. You can ask Pollen for a ruling if you want, but from my understanding of how you've written the scene it doesn't make sense. 

Also bearing in mind Sigurd is still basically off to her left, leaving literally no wind-up room for the lance in the first place. I don't have an eight foot pole and a tall person with a shield to visualise it, but I highly doubt its physically possible.