I've read that after 10 days, he'll respawn where he died, and I can go get him. Will he appear wherever I fast travel like usual once he respawns, or do I have to actually go looking for him?

I don't know. What I'm wondering is how did you manage to get him killed? He has a ton of health and has went toe to toe with dragons several times on my game.
He probably respawns back at the Sanctuary, if I were to guess.

Shadowmere has never died on me... I wish I could help you.

I would think he's respawn at the Sanctuary, but I just can't be sure.

From the wiki

■If Shadowmere is killed, waiting in a main city for 10 days then returning to where he died should respawn him on both pc and xbox versions.


I would guess from that, that you need to go get him at the place he died.

I haven't had him die yet, so not sure if this works. I do try to be careful with him on mountain climbing. That's how I usually kill a horse.

same thing happened to me problem is somehow we both fell off of a mountain and his body fell through the ground I now have the Dawnstar Sanctuary since I'm now the leader of the Dark Brotherhood.

Uhh, save often, and if your Legendary Death-horse from hell dies, re-load?