Hi, I'm wondering if anyone familiar with dead thrall spell here can help me out.
I tried to make my Forsworn Briarheart using weapons I gave him, but it seems
like he only dual wields when forsword weapons(sword or axe) is on one of his hand.
Does anyone know if there is a way to make him use both custom weapons?
Also, does anyone know how to replace thrall'd npc's clothes?

The weapon question, I'm not sure how to answer. My suggestion, before casting Dead Thrall on him, try removing things from his inventory you don't want him to use before adding the items you want him to equip.

I tried everything too.. they use whatever equipment they came with.. with the exception of arrows.. those can be switched.

I have Vampire mistwalker escorts..

I just posted in another thread that my vampire thrall is using the staff of paralysis that I gave her and she's so powerful it's kinda funny - took out a Death Lord alone by paralysing him repeatedly and then ice spiking him when he was out.

The thralls seem to be like followers, it's kind of hit and miss what they'll use. Once in the middle of battle the dark elf from winterhold put on the miner's clothes I had forgotten I'd given her before I learned she probably wouldn't use them.