
Armagnac is an oak-aged French grape brandy from Gascony, in the southwest, usually distilled once in a continuous still. It is one of the oldest brandies, and bolder and more rustic than Cognac.
The easiest alternative, taking the exact same measure. The flavor lands smoother and a bit less bold.
Other aged grape brandy
Spanish or Californian bottles work well in the same amount. When mixed as a small part, the difference barely shows.
"Armagnac is just a cheaper Cognac"
No. It is a separate brandy, from a different region and made by a different method, not a lower grade of Cognac.