I read online that there's a way (or there used to be) to fortify an Artifact using another artifact that contained N'th metal. But when I go to Fortify tab to select an artifact, it doesn't show me other artifacts. It only showed the reagents to pick from. Am I missing something? Is there something or some condition that needs to be fulfilled for this feature?
You can do it, but it's more cost effective to do it during a double XP Artifact event. You need to put some NTH into one artifact so you can break it later in another.
If you have those artifacts saved to an armory or marked as 'important' then they won't show up in your list of reagents. When you feed an artifact into another artifact you lose 50% of the XP except on XP Bonus Weeks.
Ah. That must be it. I'm assuming they also won't show up if they have not been levelled up? I have some artifacts that are at 0 level and not marked in anyway. They don't appear either. Will add some N'th Metal and experiment.
They shouldn't show up in your list of reagents if they have 0 XP in them. You can't fortify something with 0 XP
In my experience, even artifacts saved to an armory will show up to feed into others (if they have the XP to feed in). I have to mark them with the asterisk to prevent it. I haven't tested that in a few months, so I may have missed a hotfix, but that was the case up until a few months ago. EDIT: Just tested, and removing the asterisk from armory locked artifacts does free them up to feed into other artifacts. That always seemed like a bug to me.