Very easy to get - NEW 34-slot Bag in the War Within
There is a 34-slot bag that you can get very easy and is “Binds to Warband until equipped”, meaning that you can send it to any alt before using it.
This is from a treasure called Windswept Satchel, located in Priory of the Sacred Flame Hallowfall (/way 30.23, 38.75) on the edge of the big citadel.