Merlin Heraldry - Lancelot
Lancelot's device looks pretty straight-forward. My guess, it is blazoned:
Azure, two swords in saltire gules with a label of three points gules.
(On a blue background, two red crossed swords with a red label [I don't know how else to describe it] with three hanging bars)
The interesting thing here is that Lance is wearing the wrong device. His "father's" device would be the blue with red crossed swords. His sons would use the same device but with added charges to identify the sons from the father. The label would be for the eldest son. Lancelot said he was a fifth son. Instead of a label, he should have an annulet (a ring) on his device. His "eldest brother" is going to be very angry.
Also, the device is a color on a color (red on blue). One color should be a "metal" either gold/yellow or silver/white.