AussieGiant, I think Arnold has done pretty well picking up battle-related traits and ancillaries. Your going overseas could perhaps coincide with Arnold focussing on the more political and administrative sides of being a Duke. When you leave, and with Budapest safe, I would park Arnold in Vienna and give Sigismund command of the AHA so CecilXIX gets a chance at build up his avatar.

[EDIT: Ituralde beat me to it. We're a good Kaiser/Prinz combo already!]