I have most of the loot at the sanctuary and I assigned settlers to other workshops but when I go to them there isn't any weapons stored there like in sanctuary ...I assigned ppl both ways and I don't know if u need to do that even...

Only food and crafting materials are shared between settements via trade routes.

There are caravan traders who sell weapons and apparel, so I don't see why provisioners can't carry the same things. Either Bethesda add this feature or modders will.

Well that svcks,what about both ways? Or is one way enough to send them?

One Provisioner transfers between both settlements. Material/food in Settlement A, will be in Settlement B, and vice versa.