Bleh, sorry for the fail read. I get mixed up with the 5 other similar suggestions for shield<->strength relationship. Funny thing is that I think I read it properly the first few times I saw the topic and the time I happened to post I screwed up. Either way, this isn't too good an idea unless there are extra nerfs to having too low shield skill. Otherwise, I'd rather have 0 shield and a huscarl with 5 extra IF or whatever than 5 shield.
I feel the durability increase of skill is negated by being able to pick up better shields at lower shield skill anyways.
I think this will nerf shield skill itself too heavily unless it gets better bonuses.
Shield skill 2 and 1 shields are pretty much useless except for taking 5-6 arrows roughly. It starts getting decent when you can get the brown lion heater at 3 shield skill, and 4+ is completely viable. But what's the point if you can just bypass all the crappy shields at 0 shield skill?
lvl 30 build
    Strength: 24
    Agility: 15
    Hit points: 75
    Skills to attributes: 8
    Ironflesh: 8
    Power Strike: 8
    Shield: 0
    Athletics: 5
    Riding: 0
    Horse Archery: 0
    Power Draw: 0
    Power Throw: 0
    Weapon Master: 2
    One Handed: 123
    Two Handed: 1
    Polearm: 1
    Archery: 1
    Crossbow: 1
    Throwing: 1
lvl 33 build even while sacrificing skill points
Level 33 (35 569 612 xp)
    Strength: 24
    Agility: 21
    Hit points: 69
    Skills to attributes: 14
    Ironflesh: 5
    Power Strike: 8
    Shield: 0
    Athletics: 7
    Riding: 0
    Horse Archery: 0
    Power Draw: 0
    Power Throw: 0
    Weapon Master: 0
    One Handed: 117
    Two Handed: 1
    Polearm: 1
    Archery: 1
    Crossbow: 1
    Throwing: 1
Hits like a truck, still quick on his feet, has safety against range. Sure, with penalties he might get hit around the shield a little more, but the ironflesh/STR makes up for it, and it's better than what it would have been at 0 shield.
Change 1h wpf to 2h/polearm and it'll be the same, maybe even better?
The above build would be much crappier without that 5 IF