The funniest part of Fate lore is the fan theory of why some heroic spirits are depicted as they are -- some theories claim that it's because they were popularly perceived like that throughout history, while other theories claim that this is how they looked like contrary to historical depictions.
And the only thing that comes to mind is, what made people believe Thomas Eddison was a giant furry?
I think this proves the second theory
That’s just what he looked like in real life
Ok so basically Edison was summoned in a very unique way which basically goes against everything in Fate up to that point, which is why his body differs greatly from what he was in real life.
Edison is famous enough to manifest as a Heroic Spirit, however his powers as a servant are diminished because he is just so “new”. The more recent a Heroic Spirit the weaker it is generally because their actions haven’t passed into legend yet. To compensate, he manifests as a sort of embodiment of every single President of the United States through history in order to reinforce himself as a concept.
Yes this is convoluted and you were probably better off not knowing.