Due to limitations with the Spigot API(because I never cared to remove such limitations) and my time not being spent on Minecraft as much anymore I am no longer interested in attempting to fix all remaining issues with the way this plugin attempts to handle the Event. If you would like to contribute to adding an Armor Equip Event to Spigot you can do so here, otherwise. I give full permission to anyone to take over this project.
You can either take the needed parts out and stick it into your plugin or compile it as a jar and use it as a plugin depend, either way its useless without adding function to the event.
Should handle most ways to equip armor and not allow you to spam click equipping armor to get any possible benefits you might be adding using the event.