I don’t if I’m allowed to share bukkit plugins’ links here if not you can delete it.
http://dev.bukkit.org/bukkit-plugins/item-lore-stats/
Basically this plugin allows you to edit items’ names and add them lore lines that changes attributes of the item. For example if you type these to stone sword:
Damage: +4
Health: +5
You will hit base damage of stone sword + 4 (plugin also allows you to negate weapons’ base damage) and while wearing it you’ll have +5 max health.
It doesn’t have to be exactly same plugin and frankly I wonder why there are no similar plugins. I think making custom items by changing their attributes should be popular thing. When I asked to author if he was thinking about making this plugin for sponge he told me something like maybe in the future I guess I don’t remember. But I’m pretty sure even if comes to sponge that might even become at 2017.
Also I think I asked this same thing months ago and people responded me that current APIs don’t allow people to make a plugin like this. I think now it’s possible?