thinking about the gawaine/gwalchmai myth.. doi the knight sof the cross have a mantle of sorts of their own? it would explain why they can do things even without the swords
Harry referred to "the mantle of a Knight of the Cross" in Small Favor. If nothing else, it's a "mantle" in terms of being a role/position/title of power and responsibility. I think everyone is putting way too much stock in this idea that a "mantle," as discussed in Cold Days specifically, is some kind of discrete
thing, whether a metaphysical object of sorts, or some kind of quasi-sentient entity. Words mean things, and that's not quite what "mantle" means. I think the best way to consider it is as the relevant dictionary definition: an important role or responsibility that passes from one person to another. In the Dresden universe, we've seen many times that with great responsibility comes great power. That power can take different forms.
In the best-described case, when Harry assumed the mantle of (i.e., took on the role of, accepted the responsibility of, put on the metaphysical uniform of, etc...) the Winter Knight, part of that process involved literally taking into himself the essence of Winter and a measure of Mab's power. That is a part of the mantle of the Winter Knight, because it is part of what defines "the Winter Knight."
Harry took up the mantle of "Warden of the Well," if unintentionally, and as part of that, he gained intellectus of the island and authority over the disposition of the prisoners. "Warden of the Well" is a mantle in the exact same way "Winter Knight" is.
When Maeve killed Lily, we watched the passing of the mantle of Summer Lady into the nearest vessel of Faerie as a literal, visible transfer of the essence of Summer. Same with the mantle of Winter Lady shortly after. However, that doesn't mean the fiery bird form and the blue snake form WERE the mantles. Those were manifestations of the powers encompassed within those mantles. This is a difficult distinction to put into words, and I'm probably not explaining myself well, so let me give a final example:
There is a mantle of the Knight of the Cross. We haven't yet observed that mantle passing TO anyone, but we've seen it taken off. One aspect of the mantle is that archangels send the Knights to where they are most needed. One aspect is the fear, respect, and deference given to the Knights by many supernatural beings. The most obvious aspect of the mantle, though, is the Sword. A Knight of the Cross carries a Sword of the Cross. Much of the power that goes with the mantle comes from the wielding of the Sword. Bearing a Sword doesn't make someone a Knight, but the inverse is true. The Swords of the Cross are analogous to the fire-bird and ice-snake that accompanied the passing of the Ladies' mantles.