Damage Weakness

I'm creating a custom Star Wars game and I'm wondering how I can set up my Battle Droid NPC's to have the weakness to Ion damage if at all possible. I saw the Environmental Weakness Special Ability but I'm not sure how to translate that and/or the weapon damage into something that can be read by the combat tracker. Do my players just have to manually add +4 to the damage modifier before they roll or is there a way to create a custom weapon that does Ion damage and have my battle droids be weak to it?

Very interested in this myself but for Fantasy tropes. Ring of Fire Resistance for example. I have yet to delve into the rulesets much other than to look at how run dice are done (which is inconsistent apparently). I do plan on going through the LUA soon to see how to create something like this but if someone already has something that would be awesome.

What you're looking for is this effect [@Ion Damage +4]

@ means it happens when you're targeted. So when you are targeted, and the weapon has a keyword named Ion, you will get +4 to that damage.

However for that to work, you have to tell the ruleset when a weapon deals Ion damage. Simply open the weapon entry, you will see a field called Keywords there. Type Ion there (or whatever else you feel appropriate, like Blaster, Rifles, Fire, Ice, etc.), you can have multiple entries (Example: Rifle, Ion. So you might have another effect that increases or reduces damage dealt by rifles).

Same goes for a ring of fire resistance. Put this effect on the ring [@Fire Damage -4], but for that to work, all fire typed damage on the campaign (fire weapons, fire spells), should have the Fire keyword.

Other creative uses are giving a bonus or penalty when you deal that type of damage: "Ring of Fire [Fire Damage +2]", which means that whenever you deal the fire damage (notice the lack of a @), you will get the damage increased by two.

I hope that helps, let me know if you guys need any help with it