You can't play PLD with no shield very well as besides losing the stats (the shield is what balances sword stats with 2-handed weps) you lose access to Shield Bash, SHield Lob, Shield Swipe and of course the ability to block... As for an invisible shield...how would you suggest they handle the animations for the abilities I listed? Your character is going to look very silly throwing "nothing" at the monster or smashing it in the face with your forearm. PLD is a Knight not a Fencer.