Have you read the books? First off Elayne wasnt even close to Moiraine at this stage as she is surprised she can lift a single small woman not too far before this ... Something we know Moiraine match by 3x. Second, Aviendha would not be even as strong as Elayne at this point as she has just begun Channeling, even with extreme forcing she would not be as strong as Moiraine after only a few months (at most) of training. Third, Moiraine knows very well how strong the Forsaken are as she has faced several males and can at least extrapolate the women's strength from Nynaeve. She is probably the most reliable source off his information other than Rand at this point in the series. Once again you lose track of the timeline of the series and make assumptions based on character strengths MONTHS after the events in question, Aviendha is close to Elayne months after these events, but not at this point.