"Amiable sex" meaning?
Amiable sex is actually an expression that has been used for a long time, mainly in the past, to refer to women:
... and even adored as well as elsewhere, but when they do not inspire any lively sentiment, the men seldom pay them those attentions which our politeness prodigally and indiscriminately bestows upon every individual of the amiable sex.( From Love Customs in Eighteenth-century Spain)
Newman listened with an uncommitted smile and was glad, for his own sake, that he had fine feelings; but he men— tally repudiated the idea of a Frenchman's having discovered any merit in the amiable sex he himself didn't suspect.(From The American)