Q: Can the etymology of Πενθεύς truly be divorced from divinity?
Here's a name that even Graves translates merely as "grief". But as a student of Graves, this is one his translation may be too conservative. Allow me to make my case:
Yes, -εύς (Πενθεύς) is merely a genitive ending. There would be no reason to look deeper were there not a very important story about him.
But, when this word form is combined with θ, it becomes cognate with words meaning divinity and god.*
- θέωσις ("make divine") from which we get apotheosis.
- θύος ("offering, sacrifice")
- θεός ("god")
- Ζεύς ("Zeus")
The suffering of Pentheus is not merely human suffering, it is the suffering of the god Dionysus/Zagreus, who is ritually torn apart (σπαραγμός) and consumed raw (ὠμοφαγέω). In the case of Dionysus, it is the Titans; in the case of Pentheus, it is the Maenads.
For this reason, even under the argument that that -εύς is merely an ending, translation of Pentheus simply as "suffering" is factually inaccurate, based on the circumstances of his death.
*or "false cognate", although I'm not sure there's a hard distinction when we're dealing with reconstructions, especially in the context of poetry and mythmaking.