I helped both my girls night wean because it got to a stage where i just couldn't manage without sleep. They both started sleeping through on about the second or third night. When i did it, i would offer water, rock them, cuddle them, walk up and down the hall, whatever they wanted but i didn't feed them. It worked well for us, we all started getting more sleep and it it wasn't difficult or traumatic for either of us.

As for general weaning tips, i am no expert. I have read many people write to only drop one feed at a time though. Probably to do with slowly reducing your supply to avoid engorgement or mastitis issues.

As for BF'ing only for comfort. I think that is ok. BF is not just about the milk it is an important time between mother and baby. It he wants to feed for comfort and you are happy with that then i think it is fine. He is getting more from it than you imagine. As for him manipulating you, i really don't think babies have the capacity to manipulate or control their parents. It's a comfort thing, he sees his brother getting attention and maybe it upsets him a little, so he wants what makes him feel better. But his little brain wouldn't say "Man N is getting all mum's attention, i'm gonna demand a feed so i get all the attention". I know many people think babies are capable of controlling their parents, but i don't believe at 18 months their brains are capable of intentionally doing it. jmo.

BUT if you feel you want to wean then that is ok too, you need to find another way to provide comfort for him. A replacement if you like.