Just a couple things to add
- seems to be a general theme of DW to add certain card-types to classes that lacked them before, see e.g. quick for Archers/Sabers. Arts-section for riders getting another addition is a thing I look forward to, particularly since there are a couple in-class tools in current JP specifically geared towards it (Boudica, Mandricardo, Sakamoto as F2P-options, Reines as premium support)
- other than his skills, it’d be good to know what not only his NP-gain ends up being, but also how well he can generate stars on his own when needed. There are external tools for this, of course, e.g. Mozart-delivery, H.C. Andersen’s 3rd skill and/or Fragment of ‘30 CE and such. He does lack in-kit crit damage buff - yet, for that there’s other tools too: Andersen has been mentioned, el-Melloi and Merlin of course, plus his magnet is a good way to work around even Boudica’s and Reines’ Rider star-weight for situations where Casters would be too squishy.
Irregardless of all that, since I don’t prioritize gaempIay, what I want to see more of is his in-game art, the ascensions’ looks, listen to the VO, etc. The somewhat low-resolution, small profile picture of him looks appealing enough, a well-pronounced Greek NP would pretty much sell me on him already.