While browsing the texture files from .hack//Infection Mutation Outbreak Quarantine, in the file xicon00 there are character class icons and right below them is the icons for the equipment slots.
From left to right we have
Head Armor
Shield Armor
Hand Armor
Body Armor
Leg Armor
Except one thing... there is no Shield Armor in-game.
Obviously there's no shield class in the franchise, everyone has a weapon of some kind but nothing shield related. Not the say we don't see any shields in the franchise, especially in .hack//Quantum we see a ton of players using shields at the start of episode 3.
But if we look back in time, when dothack was during it's third prototype phase called Treasure Hacker, we definitely see Rachel (blademaster) and Marlo (blademaster) brandishing a sword and a shield.
(Rachel on left, Marlo on right)
But obviously in game, we never see these characters brandishing a shield. Nor the option to equip one on the character equipment screen.