Most of the fountain pens in the Patron of Arts series are piston fillers. There are exceptions, however: besides the edition dedicated to Frederick II, collectors report that the Sir Henry Tate edition also works with a cartridge or converter, and on the same technical principle as the Frederick pen.
For use and care this difference matters more than it sounds at first. A cartridge pen can be flushed out completely and stored dry for years without concern, since there is no piston seal to dry out; the trade-off is a smaller ink capacity. A piston filler holds more ink but requires that the seal be moved now and then, and that the pen not stand for years with ink dried inside it. Which system you have is evident from the end of the barrel: a turning piston knob, usually together with an ink window, marks out the piston filler; where both are absent, assume a cartridge pen. Unscrewing the barrel to check is not advisable on editions of this quality.