Heroes V - Modders' Library

I haven't worked specifically with Artifact expansions yet.
But based on the vanilla version, it all looks like this:
Attachment 73322
This is, for example, the Sword of Power. It lists everything: rarity/cost/slot on the hero (hand)/what it gives, etc. I highlighted the line that controls availability for generation (it is basically the same for both creatures and artifacts).

You also need to pay attention to the links. They point to the description/model of the artifact, etc. There must be at least something there; if the path cannot be found, the game will not launch either.

It’s easy to create a blank template; you can simply copy, say, the "Sword of Power," disable its participation in generation in this setting, and set all the "new" IDs.

That way, they will all have the model, description, and stats of the Sword of Power, but they won't appear in the game (similar to Campaign artifacts). When you have time, you can edit the required number of artifacts to suit your needs and add them to generation.