One virtue and one flaw for my magus requires some additional details, namely Personal Vis Source and Favors.
I picture Maximilian's personal vis source as external to himself, essentially a site that was granted to him at the end of his apprenticeship. This could be something relatively close to the covenant, which would partly explain his desire to join the new covenant. One possibility is that the source is in the ruins of Boura or in the Baricus river gorge (the alternate site I had proposed for the covenant here). Since it is about 30 miles away from the covenant, he could go and harvest the source without impacting his lab routine. Perhaps there are other vis sources in the area, which could be claimed by the covenant when found (during a story), but Maximilian's specific source would remain his alone. I am thinking that a source of Vim vis might be optimal for a Verditius, but perhaps an Herbam one might also make sense to help him develop his natural aptitudes even if we don't have books on this Art. Could the source provide both kinds? Essentially two small sources in the same area, both belonging to him?
As for the Favors flaw, this could be the magus who initially found that he had the Gift and brought him in. Maximilian's mater may have been a metoikos (resident foreigner), and this magus arranged for her to take Maximilian as her apprentice. He also acted as an outside mentor and, when Maximilian completed his Gauntlet, transfered ownership of the vis source to him. I am picturing him as a Criamon magus, who wanders through the tribunal visiting oracular sites and searching for visions of some kind. He occasionally asks Maximilian to perform some task for him. Some of the tasks are quite mundane and without consequence. Others involve crafting charged item for some specific (but unnamed) purpose. Occasionally, on of these tasks will lead to a story. In the past, these tasks have not been too difficult to perform nor did they put Maximilian in danger. They have sometimes been beneficial to him, although some seemed a complete loss of time. Those that might require the loss of a season probably won't happen more often than once every few years. How does that sound?