[1.09r] More fallen armor with "wrong" tech
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From 1.09r changelog
24. Fixed some tech requirements on fallen armor (different parts of the same suit unlocked on different techs).
End of quote
This implies that different parts of suits of the same "quality" should come from the same technology.
The FallenMasterHeavyPlateGreaves and FallenMasterHeavyPlateArmlets are available from the tech Arcane_Armor_Trogs while the two other pieces of the fallenmasterheavyplate set are available from the Master_Armor_Trogs.