I think you should be able to pickup any shield or melee weapon (not sure about bows/throwing, it should be considered) regardless of your shield skill or strength.
The skill or strength difficulty requirement would change to "proficiency" requirement, meaning you need to have that difficulty condition met to be proficient with the shield or melee weapon. If you are less than proficient you would take huge hits to speed/coverage, or speed/damage.
I'm a shielder so I don't have this problem, but if someone has 27 strength but no shield skill I fail to see why they are unable to hold a shield in front of them to protect from arrows? Sure the shield should probably break right away and should be slow as shit if they are trying to raise the shield (making them pretty useless to try and shield vs melee).
I think this would mainly be useful for strategus battles.