I remember Murph once said he occasionally switched to a weapon+shield mix when they were really wounded or something, to finish them off. Does anyone ever do this? Could you even win a fight with just one weapon and a shield? Is there any situation where you would want to do this?

I've never seen this in any IRE game with Knights/Warriors. Here, it doesn't make sense because you're just giving the enemy the chance to recover from their wounds and afflictions if you just use one weapon and a shield. If they're already really wounded, just finish them. I don't see the point in using a shield if you've wounded them to the point where you're about to finish them off for good.

Actually, come to think of it, the only class that I know of across IRE that can use a sword and shield effectively is only Wardancer in Imperian. Other than that, nope.

Actually it was viable when the stun immunity was shorter. You could swing your off arm twice during the stun, giving you two shots through parry/stance. Can also crush/lunge, meaning if you have them already high on wounds, you can deliver a crush and a smite down inside of one shield stun. Puts them behind on curing a bit as well, unless they come out spamming the heal chant.

Again, if you're a 1h. I don't see the point in limiting yourself to a hammer/blade and a shield if they're already at a point where they're almost dead. Just finish them, really. Unless you're trying to prove something by killing them with only one weapon, I still don't quite see the point. Maybe I'm just oblivious.

The fact that it gives you two smite downs that are guaranteed to hit through parry, stance, and acro dodging.

If they're wounded to the point where they're about to die (I.E. Mangled leg w/Knockdown) , I'm kind of guaranteed two smite downs already, arent I?

Mangled leg with knockdown isn't about dead, you still need 3800 wounds on head. In this scenario, and in the one murphy described, his strategy was 5x crush head, swap to shield, stun, smite/smite, stun, smite/smite.