Why is Eorlund Gray-Mane the only person able to reforge the swords at the end of the mod? Well, not only he is the best blacksmith in Skyrim, but the new documents added in his house tell that he already made some researches about fulgurite smithing.
Thulsa Doom, Rexor, and Thorgrim appear respectively as a Dragon Priest and two high level Draugr, so they use thu'um during their bossfight. Those monsters having a fitting appearance to make an undead version of those characters, it is purely Gameplay and Story Segregation, right? Well... maybe not. The mod uses a modified variant of the Conan setting as its backstory, altered to fit the Elder Scrolls lore. In the movie, Thulsa Doom was the head of a Snake Cult, and the mode uses snake imagery in his lair... he basically has been retconned as being part of Alduin's Dragon Cult!
Companions won't follow the Dragonborn inside the Hyborian Mound. Since the only way in consists in blindly jumping inside a hole without being able to see what's below or how deep the pit is, of course no follower enters: they're not suicidal!
Despite being Daedric-tier or Dragonbone-tier in term of damage, for full tempering the new weapons belong to the Steel tier. Remember the Dragonborn is looking for the secret of steel, not the secret of ebony or the secret of dragon bones!
Conan explains that the dying Thulsa Doom cursed him, then he gradually became weaker each day, until he eventually become trapped as a ghost inside the mound. He also presents himself as a former king. In the movie, Conan gets crowned king an unspecified amount of time after vanquishing Thulsa Doom. How long did he felt his strength abandoning him? Years? Decades?
And then, there's worse. Considering the Hyborian Mound looks as damaged as the usual Draugr Dungeon (collapsed parts, etc.), his spirit was probably trapped there for hundreds, if not thousands of years. And I Must Scream, indeed.
