We have received reports from players that they were not able to craft the Malevolent Vulcan III after claiming the fragments. The team investigated and found an issue with the recipe. To fix this they added the Malevolent Vulacan in the market where you can exchange the fragments and 1 Gravametric will return 1 of the weapons to equip.
To find this, click on the Market button in the bottom left corner of your screen.
Then scroll to the bottom to find the Malevolent Vulcan III