Being a master at a weave may mean that the weave is more powerful in every way - it is more potent, easier to weave for the channeler, and much harder to counter.

A pertinent example here is our special Kinswoman who can shield almost anyone despite being much weaker. She cites that she's practiced the weave so many times, and has a such a Talent for shielding, that she could hold one of the Forsaken - which is evidenced by her ability to hold Nynaeve.

Now shift that Talent from shielding to Compulsion, which we know from Moghedien is also a Talent. Graendal is one of the greatest in this weave who has ever lived, and she uses it as her primary attack, as shown by her duel with Cyndane and Moghedien. If her Compulsion is like the other channeler's shielding Talent, then her weave might not strike another channeler like a bullet, but like an avalanche. This is the whole point of a Talent - it is disproportionately powerful compared the what you'd expect to the channeler. This is why an exceptionally strong channeler like Rand can't Heal a bruise, but a weaker one like Semirhage can Heal the most grievous of wounds. It stands to reason that these Talent can extend to dueling, especially in Graendal's case where Compulsion really can be a weapon.

Therefore a weave is not a weave... is not a weave. Weaves can have power which can be hugely increased by the ability of the channeler. While most people could hurl Compulsion with a power of 100 at you, Graendal might be capable of ten times that potency, which would make her attacks very difficult to slice. My other personal theories are that Lanfear has a Talent for shielding, and that Semirhage could do the same with pain weaves.