Thank you for the feedback! Points 1 and 2 are now fixed, build is up :) regarding the items, relics cannot be repurchased right now; there was an error not displaying that info before, it's fixed now.
(i know it's kinda stupid to roll items that you already have in the shop pool but that's needed right otherwise you will end up with an empty shop at some point, since few relics are available right now :D)
About the artifact, make sure it's fully charged before using it, like this:
(this needs a more detailed explanation in-game, but that's true for almost every aspect of the game)