It says I can't wear armor or weapons. The guide suggests armor so I am confused. Help

It's because the law altar is on entrana, where you can't wear armour or weapons. If you want to craft laws, i suggest law running... less risk :)

yep try law running . No risk off getting pk'ed on entrana.

It says I can't wear armor or weapons. The guide suggests armor so I am confused. Help

 

The guide suggests armor because it's much better when crafting any other rune. However, you aren't able to bring armor or weapons to the law altar, which means that you'll get more easily Pk'ed/hurt by Abyss Monsters, and that you can't bring a hatchet/pickaxe, so I'd keep crafting nats.