Le Comte de Nancy is a lovable and snooty aristocrat who is basically Hassan's sugar daddy. He furnishes Hassan with an awesome location for his new restaurant, and is a regular guest thereafter. He's also suspiciously connected to Mallory (if you remember, we actually meet him in Lumière, where he frequently visits Le Saule Pleureur). For the intents and purposes of the story he's mainly a means to an end by helping finance Hassan's talent.
Le Comte is good for more than just his money, though, and Hassan also describes him as: "a kind of protective spirit, always looking out for my interests" (13.63). He's kind of a behind-the-scenes fairy godfather who represents Mallory's ever-present help and influence, always popping up right where he's needed, like right before the riot on the Champs Elysees. He's also a friendly face at Paul's memorial dinner. His remarks about Paul's downfall are true and unbiased yet mindful:
"Now look, Chef, don't mope, Verdun lost his way. That's the lesson in all this." (16.66)
It's a pragmatic understanding of Paul's death, and one that—in many ways—Hassan ultimately adapts for his own purposes.