Save illustrating the impossibility of equipping upright adamantine sword
Locate slade temple (hotkey F5)
Deconstruct the sword (the hole is covered with hatch, so no demon invasion. Also, the hell is already revealed.)
Try to assign this sword to anyone through military equip screen, specific weapon section - can't locate it in list
Assign any 2h sword to someone through military equip screen - watch the soldier picking some goblinite 2h sword
Set the material 2h sword to adamantine - watch the soldier picking nothing.