dtgreene: In Might and Magic 2, you actually can get an item to have up to 255 charges. They did, however, do something like that with the enchantment bonus of an item; items can go up to +63, and the other two bits are used for the alignment restriction. There's no overflow check there, so enchanting an item past +63 will cause its alignment restriction to change. Also, if the value in this byte is 255, the game treats the item as cursed. (Note that Uncurse Item doesn't actually remove the curse, as it sets the charge count, rather than the bonus, to 1.)

MM3-5 are better with overflow checks; you simply can't charge an item past 63 charges. (There are still some overflows in the code, however, and Swords of Xeen's scripting can trigger overflows in a few cases as well.)

By the way, has anyone tried running this editor on Swords of Xeen? It's based off the same engine, so it could be reasonably expected to work.