One other thing to remember when judging how strong Rand was at the Eye, we don't know that Aginor was 100% either. We know from Rand's & Asmodean's comments that the physical condition of the body affects how much you can channel. When Rand broke free from the AS he noted that he was in bad shape and worried about how strong he was channeling. Again Asmodean told Rand after his long range duel with Sammael in Cairhien that its dangerous to channell if the body is exhausted.

What has all this to do with the events at the Eye. By all accounts Aginor had just been released and he was not looking so good. We know from quotes in the series and RJ's Q&A that the two forsaken were sealed very close to the surface so they were aware of what was going on in the world but they were aged as well.

When Aginor went to the Eye he was probably not at full strenght himself. This did not worry him as his companion was in just as bad a shape as he was perhaps worse and he was going to face someone completly untrained. Rand was strong at the time, he was able to skim and his attack on the shadowspawn was impressive but he may not have been full forsaken strenght then and still be able to match Aginor who burned himself out because he drew what he was capable of holding on an ordinary day and never took into acount that his body had been worn down by 3,000 years.