They're in different situations, and have adapted as such yes. Just as the Blades have.
Armies don't spontaneously change. This is Imperial Legion. All actions are adminsistrative and soon become backed up by law and official organization. They are so diverse that they must have become different branches of service. They are obviously recruited in different ways, and do everything else differently as well. They share only a name. "The Legions are away in the provinces." These aren't the Legions, just soldiers in an Empire-spanning force known as the Imperial Legion. This is all anologous to the Blades as well. Institutions do not 'adapt.'
The Blades are not just intelligence agents! Jesus. Why is it so difficult for you to understand that a group can have more than just one single aspect of operations. The Blades are spies, agents, warriors, bodyguards and everything the emperor needs them to be.
Yes, but they do not do it all the same time, and one agent does not go through every role just by changing the inisgnia on his underwear. That wouls be stupid. (But I've said that already.)
Why is that? He seems very serious too me. And I doubt Bethesda put him in the game to be a twit. I doubt that very much.
Well, actually it's because Bethesda dumbed-down the main quest beyond recognition. Everything they tell you in-game about the Dragonfires and the Amulet of Kings is false or not the whole story.
So you can see it? That proves [censored]. Just cause you can see it, doesn't mean you know everything that goes on there.
How about you answer the main point? It's a curiosity, an Akaviri relic. It's a magnet for attention and at the end of a main road. The Mythic Dawn found it pretty easily, don't you think? It's nominally secret perhaps, but no one really cares who knows about it because the covert arm of the Blades doesn't reside there anyway.
... Baurus let's you leave with the Amulet of Kings because of the Emperor. It's a main plotline.
Pretty crappy main plotline. I foresee a major sticking point.
I can understand your frustration. But I can not understand your obsession with them being seperate. Why can't you just understand that there is individuality to all things? Just because they are radically different, they can still be a part of the very same thing.
Arcane, covert, ruthless, vital institutions don't care much for individuality and careless organization. There is no way Caius Cosades comes hom from Vvardenfell, opens his closet and takes out some ceremonial armor so he can go stand beside the Ruby Throne. Same organization, different departments, just like real life institutions everywhere, comparable and otherwise.