Graven shining the BLC signal means I have to throw in my 2c. First of all, in that game there are male/female (non-skins) of every character. Typically they do not change a whole lot from their baselines - the female blood priest is one of these, and because the male blood priest is morbidly obese (
http://www.bloodlinechampions.com/bloodline_blood_priest.php ) the female one is still morbidly obese. Or take the Vanguard (
http://www.bloodlinechampions.com/bloodline_vanguard.php ) whose female version is not any less imposing.
To complete the picture, let's rattle off all the other female bloodlines of the game. Only showing a portion might convey the wrong impression.
Gunner is a ranged DPS.
http://www.bloodlinechampions.com/bloodline_gunner.phpShe has a very distinctive silhouette and is fully clothed, yet is still recognizable as a female because of her long hair, her long skirt and her face, which is feminine but also distinctive.
Dryad is a healer.
http://www.bloodlinechampions.com/bloodline_dryad.phpShe is the token child, and because of her hood you only know she's a girl for sure after you hear her (very feminine) voice.
Metal Warden is a tank, although in a more supportive, ranged role. She doesn't really fit into the four-class system.
http://www.bloodlinechampions.com/bloodline_metal_warden.phpHer distinctive silhouette comes from metallic spiked shoulderpads, boots, gloves, and also the red lines running down her body (as well as a metal spine). Her primary garments are a breast plate, tight pants and metal glove things, which makes her one of the more revealing characters in the game while in LoL she could probably pass as one of the less revealing ones.
Psychopomp is a healer.
http://www.bloodlinechampions.com/bloodline_psychopomp.phpFully clothed, unmistakeably female nonetheless, is distinctive because of that headdress and messy hair.
Stalker is a Melee DPS.
http://www.bloodlinechampions.com/bloodline_stalker.phpIn this case it's all about her stance, as it is unlike any other in the game, thus making the Stalker, well, someone who visibly stalks for one. Feminity is achieved through cleavage, hair and face, but she is still pretty well-covered. Do note that most female bloodlines have rather distinctive faces.
Lastly, you should probably cut League some slack with their character designs, though. It is a lot harder to make 100ish champions distinctive from each other than it is for 25 Bloodlines. Furthermore BLC has a well-established tribal style with subdued colors, which might be an advantage versus the cartoon-ish, colorful style of League when it comes to making women women without relying on exaggerated figures and revealing clothing.