Interesting they changed the WN skill cards in skill crystals, it make more sense and make the isekai world a bit less gamey.
And I think a piece of gear that was fused with a skill card and don't had a empty slot was destroyed in the WN, the manga port was a bit more kind and made so it just got dissasembled.
The gear having a free skill slot is RNG, in the WN anything fused changed name to include the skill card monster, it made easy to recognize the effect with a little appraisal, but when fused with 3 or 4 skill cards the name didn't change after the first so only good appraisal could say the full list of effects, after all someone could try to trick the buyer, but the normal apprasial were only abe to tell the effects on the stuff, skill slots are the MC exclusive.
MC could technically recreate something close to his cheat gear with enough luck and the right skill drops.