The only thing that improves is the defense and since its just a roll it can roll the lowest defense for that item type and end up lower. A Corona has a defense value range of 111-165 where the Grand Crown has 78-113. So you can actually get a worst defense when upgrading lol.
Typically it's only really effective to upgrade weapons for the damage increase, boots for assassin kick damage, or shields for paladin Smite damage. Normal Armor/helm/shields only get a little boost in defense for everyone else.
Belts from normal to exceptional for max slots (namely Goldwrap)
Weapons (any you might like are worth it IMO, just have fun, I upgraded a Steeldriver for my Druid and then an ethereal Warlord's Trust, the final iteration will be Ribcracker)
I also like upgrading Magefist/Chance Guards at least once for 50 extra def that gets upped by Frozen Armor on sorceress or Holy Shield on paladin. You can safely upgrade Magefist to elite since they still have lower str req than Monarch for your sorc.
Not worth upgrading:
Helmets (even ethereal), Shields (not a fan of upgrading Herald Of Zakarum either: 1) str req from 89 to 142 2) you can end up with very little defense gain like in helmets' case)
If you get a PM offer, post it in the trade. Promote healthy competition instead of settling for less.
List trades and earn trust
Level up as you post
Give and Receive Likes
Discreet Notifications
Avatar & Profile customisation
Private Messaging
Bookmark Pages & Posts
Use Drafts & Revisions
Attach Images
Squelches this trader, making their offers on your trades invisible to anyone except themselves. Their trade listings will also be hidden from your marketplace.
Your squelch list can be managed and edited from Top right dropdown > Account Prefs > Squelches.
sojoonsup
3