At the end of airshow display (just before landing), the dassault rafale seems to slow down very quickly as it reach the top a final loop. It seems as if the pilot apply full airbrakes, but it seems there is no special flight control surface deployed to perform this function. How is this feature performed? Is it a special configuration of the split elevons? A combination of elevons and canard?
The Dassault Rafale has no dedicated airbrakes. By having two means of pitch control, namely wing elevons and canards, in combination with relaxed stability and an advanced FCS, it can move both into extreme deflection angles without sacrificing pitch control. This site states:
When landing, both canards and trailling-edge control surfaces can be used for braking, and Rafale may be able to use canards for braking even while in flight.
Also, having little load to carry helps. The display aircraft was most likely flying close to its minimum wing loading (which is just 276 kg/m²), and by cutting back thrust could employ its regular aerodynamic drag for braking.