Probably, if he can't cut through forearm armour with his steel blade this fight would be pointless, your character would be nigh on unassailable.
Is the ruling really that Iolanthe must lose a hand? I'd figure bashing his funny bone would be enough. The full length of his sword shouldn't even be getting close.
I say this because - he's wielding the sword in his right arm, and the shield is in Iolanthe's left. He's leading with his right, she's leading with her left. The closest points between them are Iolanthe's shield, and Sigurd's sword. I don't see her defense faltering here, it's just so simple...
You'd think so, but usually when someone writes something they write it because they're certain it will work. So confronting someone on something they're sure of is pretty difficult, it's like how often do you think you've managed to debate someone successfully enough to change their opinion on something? It's hard as hell. Judging from a third party is just fairer and takes the bite out of OOC arguments and whatnot.
This entire action required Iolanthe continue pivoting her right leg behind her left, so that once again, she fully lead with her hoplon. She leaned back a bit, to give the side of her shield closest to her head room to thrust up, and would begin ducking under her shield afterwards.
2 feet of space is between Iolanthe and Sigurd, roughly. The span of Iolanthe's body is another 1-2 feet, once she pivots so that her spear-held arm is practically withdrawing behind her.