The costs for upgrades got severely reduced (costs over 1 million usually only apply for level 315+ unique/legendary weapons once they reach an upgrade level of +18 or +19).
There is a new anvil type (diamond anvil) that allows you to upgrade an item for 3 times the normal enhancement fee, but if you fail the upgrade, your weapon will only lose 1 potential, it will not downgrade.
Events also constantly give out silver anvils and enhancement coupons (which reduce the upgrade costs by 100000 silver each), so it’s a lot cheaper to upgrade.
Last but not least, the safe upgrade limit is now +5 for both armor and weapon, so no more frustration when upgrading your armor&shield, leaving you with 0 potential at +3 or +4.