This could be a nice opportunity to use the guilds. The gladiator's guild has dummys that npcs practice on:
http://ffxiv.gamerescape.com/wiki/im.../Coliseum2.jpg
The archers guild has targets, there was that lalafell practicing on dummys in the pug guild, etc... Perhaps each disciple can "practice" in their respective guilds once they join it. I think it's ok to have limited spots and have them in the front area of the guild. It makes the guild a much more lively and interactive area, rather than having this be an instance in the back but you can utilize rooms in the back if you wish to practice with a party/linkshell. When you begin practicing you can choose a level the dummy is at if you wish to test dps and whatnot.

Further, perhaps as a high level guild quest reward you can get one for your personal housing or guild housing.