I would like Anet to add into the game mods that are currently missing from shields. There are a number of shields that do drop, but cannot be replicated in stats under the inscription / handle system.
The first group is 'Armor +x vs (creature type)'. I wouldn't mind having a Aegis of Terror / Aegis of Augh equivalent for attempting some Nightfall end-game content. But, currently these DoA Aegis greens are too expensive for my characters.
The second group contains shields that have would have double inscriptions and no handles (-2 while enchanted, -2 in stance, for example). They have dropped in areas outside of nightfall, but cannot be recreated on an inscribeable skin.