It makes no sense story wise for Welf to develop Mystery, much less reach the level where creating occulus is possible

The author has no reason to have Welf create items anyway when Fels conveniently exists

Cursed swords

What's your point? The author isn't going to have the MCs use "evil" weapons like cursed swords, not to mention you don't smith curse weapons you create them

Welf's really only good at making magic swords anyway, he's a normal smith otherwise

Cursed Swords aren't evil. That's just a preconceived notion, like all monsters must die(xenos)! I would like him to use Blacksmith & Mystery to craft a suit of armor, using mystery for the cloth part & Blacksmith for the metal on top! Imagine shirt & pants made of undine & salamander cloak & armor made of Cadmus hide!

It still wont happen tough. Welf wants to be a smith and not some strange item creating smith. He doesnt get anything from the Mystery DA. He as well is a pretty medicore smith giving him an ability which he needs to practice for years to create something usefull wont happen because the Story ends in 6 months or shorter in universe time. It as well doesnt have anything to do with what Welf wants to do because DAs appear for personel exerperiences and Welf doesnt create anything he smithes most of the time or fights in the dungeon.

"Cursed Swords aren't evil. That's just a preconceived notion, like all monsters must die(xenos)!"

That's why I put evil in quotation marks like this ("evil")

"using mystery for the cloth part"

I don't think you understand what mystery does. Making clothes would be something else and your suggestion implies that you're just stitching this stuff together

Salamander's wool & Undine Cloth seem to be more mystery than blacksmith to me, since Fels did something similar with Reverse Veil

Salamander Wool and Undine Cloth are made by Spirits, not people with the Blacksmith or Mystery DAs.

Oh, okay.