This could perhaps be accomplished with a basic excel sheet or just keeping notes about you characters advancement in LI stats, but, well...
I use Alt Inventory
to keep track of what I have in Bags and Vaults, but is it possible to keep track of your Characters Gear, Stats and LI items, down to individual Relics slotted to LI's somehow?
Since I do a lot of crafting I also do Crafted Relics that I exchange for Insignias or Devices at the Guild Master and more than once I end up with either the wrong item or duplicates which I dump to AH. Something in game helping to keep track of this would be very useful since the more Characters you have, the more difficult it becomes to keep track of these things.