Nasu: It's what I was talking about before, the fun of liberal interpretations. For example, in the original legend, you get these brief, like two-line descriptions. Something like, "Cú Chulainn (*) has a spear called the Gáe Bulg. The spear is said to always pierce the heart of the wielder's foe and burst within it." And that's it, that's all you get. But if you look at it the other way, you can do whatever you want as long as you make sure to adhere to those two lines.
Nasu: It's why I've always been opposed to turning contemporary figures into Servants, because they're extensively documented. That said, Fate GO has such a huge volume of Heroic Spirits that I violate that taboo.