A/N: It turned out a bit short; chapters will likely get longer as the arc goes on. For now, we're still establishing.
The Mantle of the Maiden is an interesting phenomenon, for many reasons. Each of them has potential for different applications, with sufficient study.
First is the concept of transference. The Mantle is a realization of soul transfer; even if only the smallest echo of the previous Maidens remain, the concept is sound. The ability to implant a soul into a new body has many potential uses; you can see many situations where your mortals might benefit from such action. While you cannot benefit directly from this concept, the echo of a soul is still useful to you via Assimilation... and you are admittedly curious: what would happen if you consumed the Mantle of a Maiden? What information might be gained from such an action? Unlikely as it is, the idea is... interesting.
Still, studying the phenomenon is difficult. It is likely that Penny may be of use in studying this; a deeper analysis of how her soul connects to her vessel may provide insights in this area. And, naturally, there are always more Maidens to be studied.
Second, and more immediately useful, is the method by which the Mantle strengthens its bearer. From what your senses indicated, the interaction is twofold: First, the Mantle generates a constant stream of magic by interaction with the bearer's Aura... the exact mechanics of this are unclear, although you can replicate it to a degree through the Frozen Flame, and your Arbiter's link to you acts in a superficially similar fashion. Then, part of this power is diverted and combined with the echoes of the previous Maidens, weaving many instances of Aura together to create a stronger whole. The result, a shifting, refractory Aura is... interesting. You had little time to study it in detail, but you gained enough knowledge to experiment with such on your own. Penny, again, would be of great use to this line of thought; she already turns your power into more of her soul, and you expect you could bolster it without significant complication.
Then again, your Arbiter has a ready-made supply of your power at all times... Perhaps, when her recovery completes, she will assist you with your experiments. Certainly, a boost to her Aura's efficiency, even a small one, would make her far more threatening.
The final piece that makes the Mantle interesting is simply the mechanics of its magic. While the effects are similar, it is mechanically distinct from your own – and that which you have taught your mortals. Far more similar to a Semblance; the elemental manipulation is powerful, especially amplified by the Mantle's echoing effect, but it is unlikely that a Maiden will ever perform the type of dynamic spell usage that your mortals will eventually be capable of... and the power is largely static, building only with every succession. With practice, your mortals have grown and this pattern will continue: even Janus of Zeal continued to grow in mastery throughout his lifetime. The Maidens, however... they may become more skilled in wielding the power that they already possess, but their reserve of power cannot grow larger until they pass the Mantle on, nor can they increase the amount they channel at one time.
You suppose that, in thousands of years, the Mantle may accumulate enough power to be unchallenged... but for now, it is a surmountable obstacle.
You have made progress towards satisfying a Curiosity.
Blake wakes shortly before sunrise, and takes the opportunity to scout around the cave entrance. Her night vision allows her to do so with ease... and her old training is useful in some ways, when she finds a path nearby. She kneels, considering it, and wincing only slightly. Her body has recovered fairly well under the ministrations of her Aura, and her soul burns brightly enough. Time will be required for her to return to full strength, but for the moment you are unconcerned.
"...Well, whenever we are, they still have horses." She idly traces the outline of a hoofprint in the road before noticing the shape below it. "...And Grimm, by the looks of it." She looks up, her eyes tracing the road in the direction both prints travel. "A hunting party, maybe? That could explain why we haven't run into any Grimm so far. They'd be drawn to the battle... There must be something valuable in this area, I guess. A settlement, or an outpost, or something. It would make sense; history says that Vale was built here to take advantage of the terrain's natural defenses."
From where did they travel?
She blinks momentarily. "...Good point. They must have come from somewhere... if it is a military outpost, though, they may not be happy with us just wandering into it. Still... with no information, I guess we just have to pick one. What do you think, Obsidian?"