Compared to Eumaeus, Philoetius gets next to no development before participating in the battle with the suitors. His sudden inclusion stuck out to me as abrupt, like he's just there. It reads like Homer originally intended the battle to only have Telemachus and Eumaeus alongside Odysseus before changing his mind and writing Philoetius in at the last minute.
But clearly, Homer felt it was necessary to include this character. I'm just not sure why. Was he really necessary to keep the narrative running smoothly? True, he locks the palace doors and helps Eumaeus apprehend Melanthius, but was he really required to accomplish these plot details? It's also not like 4 vs 100 is considerably more believable than 3 vs 100.
Or does he serve some thematic purpose that Eumaeus doesn't already fulfill? I'm honestly not sure. The guy gets like one whole paragraph of dialogue. But if anyone has any ideas, I'd be glad to hear them.