As the title suggests i'm suggesting adding custom enchants for all tools and armor a plugin like can be found below I already showed @irritatingness this but it needs to get public opinion on it. https://www.spigotmc.org/resources/crazy-enchantments-new-gkitz.16470/
Since this is survival based, to spice it up things like this I believe can add a lot to the ways the game can be played. Though I cant seem to find the list of enchantments on that site, until i see them im neutral.
I like the idea of custom enchantments, though some of the ones in this plugin may be a little bit much, we'd probably have to disable a few if possible or find a different plugin. This will likely not go anywhere unless there is a good amount of positive support, as it is a rather large modification to the game.
Come on robo you click the text saying list of enchantments you know the one right above features but heres a direct link https://github.com/kicjow/Crazy-Enchantments/wiki/Enchantment-Information-Page
All custom enchants can be disabled, removed, edited, etc straight from a .yml file called customenchants.yml under crazy enchants folder in the plugins folder you can also easily add or remove ones.