@FlatEarth Honestly, you make a good point. Given how powerful Edi is, I personally think that if he did fake his own death it was so he can run ahead of the slow as fuck party and kill the Demon Lord himself so as to get it done and over with. This could explain why the Demon Army was defeated so quickly.
If, however, he didn't fake his own death and has simply been recovering from a serious injury, then that could explain why he hadn't returned to either the party or Philomena. They mentioned that his staff was completely drained of magical energy, so if we assume he lost a lot of his mana due to the fight then he couldn't teleport to anyone and wouldn't be able to use any magic to locate the rest of the party. In that situation, the best way to survive is to find a rock to hide under and wait until his magic recovered enough to teleport home to Philomena.
I really hope he simply went ahead and killed the Demon Lord since that way he wouldn't be hurt, but at the same time I don't because that means he didn't let anyone know of his plan which led to Philomena believing he died. The next chapter can't come soon enough. :I