The idea for the mod came about during my latest Icewind Dale game. Reading through the item descriptions, the developers really took a lot of time to give many items an elaborate backstory. In many cases, I felt that an upgrade was a chance to tell a bit more of the story.
There were two main drawbacks to an Item Upgrade mod for Icewind Dale--first, you can not rely on some items being in the game, as many are part of random treasure lists. At least two items available for upgrades may not appear in any given game. The other issue is that, unlike Cromwell in Baldur's Gate II, there's no 'magic dwarf' available early to facilitate upgrades. This means that the upgrades are accomplished through a variety of means, which was good in the long run as it provides more of a role-playing flavor to the mod.
Six items were also added from Baldur's Gate II, as they seemed appropriate for where they were placed in the game.
Vexed Armor can be made safe if the party learns the true name of the demon after acquiring the armor.
I'd like to think the upgrades are straightforward enough that players can discover them with a little thought, so further details are available in the form of spoilers: