I like a lot of things about your post.
Mostly the idea of a secondary mode for the shield.
I dont know why you would limit it to specific models, however.
Pressing x or something on the shield changes the position, maybe?
With multiple positions available to the user, this could be pretty cool. but you would need to balance it with a drawback. the over head already has an obvous drawback. death from right in front of you.
I have also been thinking for quite some time that there needs to be a different form of shield use also available.
There is no reason a shield should not provide PASSIVE protection.
I can see why it does nothing on the back. game balance.
but let me propose another change for you:
Pressing the modifier key on the shield changes it from active use to passive use.
Meaning: it stays on the users hand, but he gets to focus on the single hand weapon use without the normal drawbacks of using a shield. No weapon penalties.
The shield stays passive on the left, and still blocks attacks and incoming projectiles from that direction.
This is not very OP since it opens up 50% to 65% of the shielders body (his right hand side) to attack and projectiles at all times, and he will have to manually turn into the incoming attack with his body to use the shield. But this will open him up to multiple opponents.
Active blocking (normal)= close to 100% coverage from the front, with weapon penalties
Passive Mode= passive coverage where the shield model is located on the left hand side. better swashbucking, no wpf penalties
Im a 2H, BTW. So lets get some real shielders feedback on if this is retarded or not.
if you arent a shielder, I dont actually give a *********