FOR THE CREPES: Combine eggs, milk, water, flour, Cognac, sugar, salt and melted butter in a blender until smooth batter forms, about 10 seconds. Transfer batter to medium bowl.
Using pastry brush, brush bottom and sides of 10-inch nonstick skillet very lightly with melted butter; heat skillet over medium heat. When butter stops sizzling, tilt pan slightly to right and begin pouring in scant 1/4 cup batter. Continue to pour batter in slow, steady stream, rotating wrist and twirling pan slowly counterclockwise until pan bottom is covered with even layer of batter. Cook until crepe starts to lose opaqueness and turns spotty light golden brown on bottom.-, loosening crepe from side of pan with rubber spatula, 30 seconds to 1 minute. To flip crepe, loosen edge with rubber spatula and, with fingertips on top side, slide spatula under crepe and flip. Cook until dry on second side about 20 seconds.
Place cooked crepe on plate and repeat cooking process with remaining batter, brushing pan very lightly with butter before making each crepe. As they are done, stack crepes on plate (you will need 12 crepes). (Crepes can be double-wrapped in plastic and refrigerated up to 3 days. If crepes have been refrigerated, bring them to room temperature before making sauce,).
ORANGE SAUCE: Adjust oven rack to lower-middle position and heat broiler. Add 3 tablespoons Cognac to broiler-safe 12-inch skillet; set over medium heat just until vapors begin to rise from Cognac, about 5 seconds. Remove pan from heat and wave lit chimney match over cognac until it ignites; shake pan until flames subsides. (Cognac should burn for about 15 seconds; re-ingite if flame dies too soon).
Add butter, 3 tablespoons sugar, and 1 cup orange juice to cognac; simmer briskly over high heat, whisking occasionally, until many large bubbles appear and mixture reduces to thick syrup, 6-8 minutes. (You should have just over 1/2 cup sauce.) Transfer sauce to small bowl; do not wash skillet. Stir remaining 1/4 cup orange juice, zest, liqueur, and remaining tablespoon cognac into sauce. Cover to keep warm.
TO ASSEMBLE: Fold each crepe in half, then in half again to form wedge shape. Arrange 9 folded crepes around edge of now-empty skillet, with rounded edges facing inward, overlapping as necessary to fit. Arrange remaining 3 crepes in center of pan, sprinkle crepes evenly with remaining tablespoon sugar. Place skillet in oven and broil until sugar caramelizes and crepes turn spotty brown, about 5 minutes. (Watch crepes constantly to prevent scorching; turn pan as necessary) Remove pan from oven and pour half of sauce over crepes, leaving some areas unsauced. Transfer crepes to individual serving dishes ans serve immediately, passing extra sauce separately.