Hi I made a specific forge how I do to make a weapon set appear only in that category?

Set a Keyword for the new forge like "MyNewForge." Next, head over to the Constructible Object record category and create the item recipes, setting the Workbench Keyword setting to "MyNewForge." Then, when you use the forge, only your weapons will be displayed in the menu and not the defaults.

The organization of the crafting menu itself is hardcoded, but so long as you use the correct Keywords, you can set up your forge so that only your specific items show in the crafting menu for it.

but in what category will fall?

That's determined by the keyword on the created item(s): WeapMaterial*

And in case you are wondering: these categories are hardcoded and cannot be changed.

I have added weapon material steel to the weapon and in the recepy I set it required steel and that special forge , I added the keywords , basically I just copied the setup of skyforge ....

so when I go to forge ( I have 100 the skill )

I see all the weapons apart the one I need to create .... why?

Out of curiosity, are you trying to set it so that you can only create your weapon at that forge, or to set it so your weapon can only be created at that forge?

If you're looking to only see your weapons in the list, you need to remove the CraftingSmithingForge keyword from your new forge.