I agree with you on the azureus...its a female. The cobalt is a little more difficult. I have multiple females whose toe pads are much larger and the another thing I look at is shape. I am leaning male but thats tough because you are not scared to feed them
Most of the times the females tend to have smaller toe pads, be a little longer in length, and have a stomach that hangs lower (not always wider). I have my fair share of tincs...10 pair...but I still would not consider myself an expert. I know my feeding habits and I know how they fill out under my care...but it can be tough going off a couple pictures of frogs in others' care.
I'm thinking the azureus is just a little fat. She seems a little small for eggs, compared to some adults I've seen at shows that I swear had to have gone 2.5". She's a great eater but the cobalt is a bit shy and won't eat until I'm out of sight.