In a food processor, puree 4 of the bananas until smooth, then set aside. In a large saucepan set over medium heat, whisk together the agave, cornstarch, salt, egg yolks and coconut milk until smooth. Bring the mixture to a rolling boil, then reduce the heat to a simmer. Cook, stirring constantly, until thick, about 10 minutes. To check for doneness, coat the back of a spoon with the pudding and run your finger down the center of the spoon. The pudding should hold a clear, clean line. Remove from the heat, then fold in the pureed banana. Refrigerate until cool, at least 2 hours or up to overnight. The pudding will continue to thicken as it cools.
Slice the remaining banana. Crumble 2 wafers into the bottom of four 10-ounce ramekins. Divide the pudding among the ramekins. Top each serving with banana slices, toasted coconut flakes and another crumbled wafer.