After unlocking the Tournament gameplay mode and joining the weekly event in, you can obtain Mint Condition Gear. Just like any other Gear in your inventory, Mint items can be common, rare, epic or legendary.
The “Mint” Condition means that the item is brand new and can be equipped to advance in the Tournament nodes.
The Mint condition is available for the duration of the current weekly Tournament period. After the period ends the mint condition disappears. The item itself will remain in your inventory and can still be used in the other World Dungeons and Badlands.
With each new tournament you join, you will receive new Gear in Mint condition to be used in the current weekly event.
You can recharge and empower a Mint Item to increase its power during the Tournament. Once the Tournament is over, the Mint condition will disappear however the newly gained power of the item will remain.
Furthermore, from the "Collections" tab, you can craft the item again and the "Mint condition" will be again available.
Also, "Mint condition" of one item can be regained or obtained for one week during Tournament by choosing to 'Mintify'. This option is available by clicking on the Item and choosing the 'Mint' option presented. It should be the 4th tab above the name of the item.