Is there not some mention in one of the first passages where Talaan is introduced that when Nynave judges her strength, she feels that Talaan is very close if not equal in strength to herself and that she was fairly certain that, with how young Talaan is, she still has very far to go until she reaches her max thus putting Talaan's effective strength at a greater level than Nynaeve? I know that later in the series when Talaan confronts Nynaeve and pleads that Nynaeve take her to the White Tower to be enrolled into the novices, Nynaeve makes some comment about how young Talaan is and how the Windfinders would skin her alive if they stole her away; I vaguely remember Talaan heatedly responding that she was 5-10 years older than she appeared (hence proving even more that she is so strong in the power to have started slowing even earlier than Nynaeve herself). I know, I know, Nynaeve had a block to begin with, but she still had slowed in her blocked state when she was the Wisdom.