An unguent is a soothing preparation spread on sores, burns, irritations, or other topical injuries; an ointment. It is usually delivered as a semi-solid paste and is often oily to suspend the medication or other active ingredients. See also salve.
Some remaining ceramic Parthian figures show red tinting on hands and feet, indicating men stained their skin with henna during the Parthian period, lending weight to the probability that Royal Unguent was a henna mix as we understand it and meant to be used for body art.
However, an Assyrian bas-relief of a royal procession from Nimrud in 865 BCE at the British Museum still has traces of red colorant on the soles and toes of the king and some of his courtiers.
This can be interpreted to indicate that henna was appropriate for royal men’s feet on ceremonial occasions, and potentially places "Royal Unguent", if this can be interpreted as a henna mix, in a much earlier period.
Unguent wasn't in the best of form as he dove out of the way of the smoking mass.
This suffices, for the druids fear that Unguent might awaken, and his loyalty in the situation would be uncertain, for he has descendents on each side.