Name for skill could be Thigten Armour
arms slots minimum).
It would increase protection gained from wearing armour, the more the more
slots target has covered with armours (ring, amulet, bracelet slot maybe
exluded).
Fumble could lower targets dex. Doing skill would take long, and it would last
some time or until any piece of armour worn when it was tightened is removed.
You coud use it only on other player whom wears enough armour (torso, leg,

You could only use it on other (not youself) plyer who has enough armour,
torso, arms ans legs covered, minimum.