Gilded of the Ethereal

Copied from previous achievements and comments

/run local n=tInvert(Enum.ItemRedundancySlot),a;for i=0,16 do a = C_ItemUpgrade.GetHighWatermarkForSlot(i); if a < 720 then print(a, n) end end

Copied from Belazriel but changed formatting so the full script is shown:
/run local n=tInvert(Enum.ItemRedundancySlot),a;for i=0,16 do a = C_ItemUpgrade.GetHighWatermarkForSlot(i); if a < 720 then print(a, n) end end

I couldn't find it documented anywhere, but the way it is working for me is:

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• After one toon achieves Gilded of the Ethereal, then a specific Gilded-level upgrade for any Warband toon will be 10 if and only if any other toon in your warband has achieved that upgrade already.
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• Crafted items DO count -- e.g. a crafted 727 will mean your other toons get cheap upgrades to Myth 7/8 (727).
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For example if Bob has a Myth 5/8 helm, then Joe can upgrade helm to 5/8 myth (or 8/8 Hero) for 10 per step, but would have to pay 15 for the next step.