As has been said, it was during the KoD trolloc attack. It was LTT who was doing it really but they are essentially the same (especially now) so what LTT can do, Rand can do.

During the attack, Rand creates 6 Blossoms of Fire at once.
Three weaves go into making one Blossom (Earth, Air, Fire)
That means to create the 6 blossoms took 18 weaves woven simultaneously.

However it is also written that LTT makes 6 deathgates at the _same time_ as he makes the blossoms. Again it takes 3 weaves (Spirit, Fire, Earth). That means another 18.

That means that according to the text, the absolute minimum amount that LTT/Rand can do is 36 simultaneous weaves. And those are actual complex weaves used to attack rather than simple glowing balls. (Though to be fair to Egwene, she was under forkroot so I assume she could do something real with her 14 weaves in other situations)

The arrow of fire thing is in addition to this, and its a bit more confusing. During the above scene, LTT does not do AoF since those require raised hands. However he does complain about not being able to raise his hands, which suggests that he could potentially have done the Arrows in addition to all that. Arrows of Fire use 2 weaves (Fire, Earth). So that would add the minimum to 38.

Though I do think, based on the text, that to create the arrows really did require just 2 flows rather than a hundred. The weave for the arrows is called "intricate" so I think it was the complexity of the weave that caused a constant stream of "arrows", rather than having to create a unique web for each one.

So any AS (including Egwene) could create Arrows of Fire, if they simply had the necessary skill, and knew how. A shame that Egwene does not have either or the Seanchan attack could have ended very differently. Could Nynaeve have created AoF? In truth I doubt it, but I think she is still superiour to Egwene. Neither of them could be considered elite-channelers, but Nynaeve is closer. Egwene has simply never done anything that would even suggest she is especially skilled. Like I said before, she has mostly been doing politics. In a pure test of OP, Nynaeve would easily dominate. And not just in healing but in every area.