I'm not too sure about that. A mantle is something that contains power and if a wizard is strong enough to be considered for the position of Merlin, they wouldn't need that power. I think we are putting to much importance on the existance of mantles. It would be kinda of cheap if every power up Jim gives to his characters was mantle based. If Harry isn't the Merlin, he wouldn't gain the Merlins power through a mantle. It would be more realistic if Harry obtains Merlins journels and learns from those
Lol sorry if that confused you. Power in the form of a mantle is inherited, while power from a title is earned. THE Merlin of the White Council earns his power through training its not given to him from a mantle. Otherwise a regular human could be given the mantle and become super powerful without the training and discipline they would require to control it
There are Mantles and mantles. The Fae Knight/Queen Mantles are magical constructs which seem to be discrete entities from their hosts. These can be passed around and grant overt magical powers. Little "m" mantles are a little more mundane - one could don a mantle of authority for example - there is power in the position/title itself rather than giving an actual magical or physical power boost.
The title of Merlin probably doesn't come with a magical power boost but it definitely comes with the power of authority and political weight. The position might also come with secrets, special access or special contacts not privy to others - that is power in a different form.
The position of Warden is a little more ambiguous. Ebenezer already referred to the position as a mantle, but I think he meant it as people normally do - a position with special rights and responsibilities. The mantle of Warden does seem to come with its own power boost in the way of limited intellectus, but its real "power" is in giving Harry control over the prison and Demon Reach. He's been granted authority rather than a direct power boost.
So yeah, when people talk about Mantles or mantles I think we need to clarify what we mean: if we are regarding a specific role as being a Magical construct with some cosmic purpose, or a more mundane position. It's important because higher powered beings in DF have consistently been in or previously held positions of authority and/or responsibility. It's almost as if they are inseparable past a certain point, so Harry WILL most likely gain extra responsibilities for every power-up he gets but not every mantle in DF is a magical contsruct (that would be silly).
Also, it's been said over and over and over, but power does not immediately or necessarily mean quantifiable magical energy units. Power fundamentally is the ability to act. There is physical power, magical power (in seemingly quantifiable units), there is knowledge, there is wisdom, there is authority, and probably many other forms of power.
In the books we see that Harry has much more metaphysical mass than most Wizards, yet others who don't have as much are far more powerful than Harry is because they have authority, knowledge, and wisdom. For example, Luccio is able to do more powerful fire spells than Harry with less energy because she has finer control. Same thing with the Archive, she has crazy amounts of knowledge that allows her to wield magic in ways Harry probably couldn't imagine. Harry could beat Fix butt naked because of his absolute knowledge of his surroundings. However, Marcone is more powerful than all of these people in that he can hire the best hit-men in the world to do his bidding since after all, money is power.