§ asea aranaite >> asea aranion ’kingsfoil’ (WR:394)
§ athelas (ibid.)
For the formation of aranaite *’royal’ compare maʒiti ’handy, skilled’ > Q. maite (MAƷ-), kiryaite beside kiryăva (PE16:113) and Q. aran ’king’ (WJ:369). Aranion is transparently the Quenya genitive plural of aran.
For the etymology Tolkien gives the root √ATHA with Q. asya- ’to ease, assist, comfort, the noun asië ’ease, comfort’, asëa ’as name of plant ”athelas”’, S. athae, ath(a)elas and the verb eitha- ’to ease, comfort’ (PE17:148).