upgraded_from_disabled=true if they are not eligible for the system.
The Synthesiser can be found in the Memory Nexus. To use the Synthesiser, you must place three Rare fractured items of the same item class. The size of the item does not matter, but the item class must match. For example, one-handed maces and sceptres are considered two different item classes.
For details on the synthesising process, see synthesised item.