Can anyone tell me how to make a splash potion of weakness

Can someone please tell me how to make a splash potion of weakness?? Thanks

:)

 

Curing Zombie villager issue

So I'm trying to get the achievement for curing a zombie villager and went online to see how this is done.

Best method I found.

Step 1. Trap zombie villager in a fence.

Step 2. Throw splash potion of weakness at zombie villager.

Step 3. While the zombie villager is under the effects of the splash potion of weakness feed it a golden apple.

I've gotten as far as step 2. The issue I'm having is that whenever I try to feed the zombie villager a golden apple I end up eating it instead of the zombie villager (and yes I know how to tell the difference between a regular zombie and a zombie villager).
The left trigger Icon says "cure" when I'm targeting the zombie villager but what happens when I pull the left trigger is me eating the golden apple. I've tried to cure a few zombie villagers now and it's the same thing every time.

Am I doing something wrong or is this part of the game just broken for me?

 

Let's discuss your most powerful poisons.

You can use a weakness to magic potion since elemental damage is still magic. That's what I did in Oblivion. I had a weakness to magic enchant on my bow then I cast whatever element was needed.