No, you are perfectly correct and fine in your understanding that magic needs a sort of reasoning to be used properly. :) My only problem with that first part, meaning with the magic, was that, through discussion, we decided that the same (or similar) spell effects can be reached via different steps on certain occasions. So perhaps they do not do "Bladesong" magic because a witch's process is different; but the magic can definitely been seen exhibited by any other, considering they know how. Really, it's just mean "warning" you that, in pure technicalities, this specific Bladesong magic is rare, but that in no way means that you won't be anyone else doing identical spells in a similar way.
On the connection, yes, as explained it was explicitly stated in the interest check, although not yet in the OOC. My fault on that. It will be mentioned in the FAQ, and I'll change the sheet in the Role part to state that the role must be within the D'Cerf. Thanks for helping improve the RP. If you hadn't made Jocasta, I never would've found out I forgot to mention the connection to D'cerf. Again, thanks! :D