Dungeonborne’s version of legendary gear is called Heirloom. You can craft Heirlooms in the game but only after finding relevant legendary fragments.
There are two (technically three) legendary gear you can craft after finding legendary fragments at various locations in Dungeonborne; The Divine Sword and The Divine Crown.
Notice how I said there are technically three legendary fragments? Well, yes because the third fragments, The Moon Pendant, is required before you can find The Divine Crown and The Divine Sword.
How to Get the Moon Pendant in Dungeonborne
The Moon Pendant legendary is unlocked after you find the Moon Pendant fragment, an Epic Material. The Moon Pendant can only be unlocked during the night and full moon.
If there is a Full Moon during nighttime, head to your Training Room under the Selection Menu. Once you load in go to the alter and pray to get The Moon Pendant fragment which then gives you access to The Moon Pendant crafting option.
Make sure to exit the Training Room after obtaining it to keep the item.
How to Get the Divine Crown in Dungeonborne
The Divine Crown is unlocked after you go to Sinner’s End (Casual or Classic) and pray at the shrine.
In my experience, it is most commonly found in the northmost center room. Note that only one fragment spawns per map.
How to Get the Divine Sword in Dungeonborne
Lastly, we have the Divine Sword legendary Heirloom which can only be acquired after you get the Moon Pendant and the Divine Crown.
You need to equip The Divine Crown legendary heirloom (or fragment) and the Moon Stone Necklace (or fragment) or have it in your inventory before dropping into Sinner’s End.
You can then craft the Divine Sword using the fragment you obtained, along with any required materials (such as Mithril Tokens or Star Fragments).
Note: Both the Moon Pendant and Divine Crown will be consumed when you unlock the Divine Sword, so you will need to re-farm these items if you want to obtain them again.