There have been several film adaptations of the novel. I have only watched the 1937 version, and I would recommend it to everyone who likes retro films and Victorian love stories. Here is the duel scene where you can see Russendyll and the "dashing villain" of the novel, caddish Count Rupert of Hentzau, played by Douglas Fairbanks Jr.
Another famous actor in this film was Raymond Massey who also played Citizen Chauvelin in the 1934 version of the Scarlet Pimpernel.
There was also the screen version from 1952 which I haven't seen.
You can read the novel over here: