If you are looking to add material compat to Enderswords, Imbued Gear adds two pretty unique ingots: Puresteel and Voidsteel. Both materials have a ToolMaterial (radiant and nihil, respectively), so you could probably hook directly into that, or use it as a reference at least.

Puresteel and Voidsteel item registration

Puresteel tex

Voidsteel tex

Example of how to directly hook into my configurable ToolMaterials: IgConfig.INSTANCE.getMaterials().getTools().getNihil()

If you want to really above and beyond, we could talk about how to make them Modifiable too, so they have the same on-hit passives as the Radiant Broadsword and Nihil Blade, and I'd be happy to help with recipe ideas too.

I've actually made the modifiers part a lot easier on both of us. Can be done with datapacks now. You can just slap this file into data/<modid>/item_modifiers/, rename the items to your actual item identifiers and boom.

modifier_compat.json

For the most part, I take the base sword's speed and attack, lower the attack by 1, raise the speed by 0.2, and slim the blade down a little bit on the texture. They have a right click ability to throw pearls, but other than that, they're pretty basic.

If you're wanting to hook into your effects into that ability, I can always publish the source here on github with my base, and you can tweak the code to your heart's content. I'll pull and compile. :)

For the two swords I mention above my effects are passive on-hit, so they shouldn't conflict with the pearl at all