Precision weaving is merely the ability to weave sharp and focussed weaves, and there is no evidence that anyone weaker than Egwene can do it, and we've seen a considerable amount of weaving from channelers of other classes. There is quite a lot of evidence that strong channelers are capable of these weaves. A precision weave is focussed, and similar to the focussed energy of a circle - which is why strong channelers can sever without a circle.

I don't think Aes Sedai can sever channelers unaided. They need to make a circle - maybe not thirteen - but definitely more on. I don't believe that any of those males were gentled by single sisters.

Nynaeve says that the sharpness of the shield is the key to making it a stilling weave - it's actually a normal shield without that, as she demonstrated with Moghedien. Therefore considering I believe that precision weaving is linked to strength in the power, and considering the stilling weave is defined as a keen-edged shield, I think that only powerful channelers can pull it off.

Some examples of precision weaving...

1. Asmodean - TSR (The Traps of Rhuidean) … “Lying there , he stared up at three bright ribbons … Hard as steel , sharp enough to make a razor seem a feather …”

2. Cyndane - WH (With the Choedan Kal) … “A razor-thin flow of Air sliced the fellow’s beard in two as it took off his head …”

3. Moghedien - TSR (Into the Palace) … “Before thought she struck out , weaving a hammer-hard flow of Air to smash that face. In an instant the glow of saidar surrounded the other woman … and Nynaeve’s flow was sliced razor clean …”

4. Moghedien - TSR (Into the Palace) … “For a moment she could only stare. One of the figures , an odd animal shaped roughly like a pig but with a large round snout and feet as wide as its thick legs , stood where the seal had … It was not really there; the thing was woven from Air and Fire, in flows so minute they made cobwebs seem cables. Even concentrating she could barely see them. She doubted if Liandrin and the other Black sisters could have …”

5. Nynaeve - TSR (Into the Palace) … “The knife-sharp shield that Egwene had used to still Amico Nagoyin sprang into being …”

6. Nynaeve - TSR (Into the Palace) … “the Forsaken struck with a complex weave of Spirit streaked by Water and Air. Nynaeve had no idea what it was meant to do; frantically she tried to cut it as she had seen the other woman do , with a keen-edged weave of Spirit …”

7. Egwene - TDR (What is Written in Prophecy) … “She set the patterns of the weaving , readied them , making the threads of Spirit much stronger , this time , thicker and heavier , a denser weave with a cutting edge like a knife …”

8. Lanfear - TFOH (Choices) …”It was not at him directly that she struck this time. It was at his link to saidin. Panic rang the Void like a gong at the first knife-sharp touch , the Power diminishing as it slid between him and the Source. With Spirit and Fire and Earth he cut at the knife blade …”

9. Moghedien - TSR (Into the Palace) … “Moghedien’s axe of Spirit waxed and waned in sharpness , but that would not matter if the woman managed to drive it home…”

10. Nynaeve - TSR (Into the Palace) … “she had to keep forcing it back to a razor edge; the woven flows did not want to hold the keenness.”

11. Nynaeve - TSR (Into the Palace) … “Examining what she had done , she saw it had not been as complete a victory as she had wanted. The shield had blurred its sharp edge before it slid home. Moghedien was captured and shielded , but not stilled…”

We've seen weaker channelers play with shielding. Moiraine merely puts all her strength into a shield and hurls it as the Sister from the Black Ajah, Merean. It bounces off. I don't think they have the natural ability to do what any of these channelers above can do, which means that they cannot still people unaided, even if they have the strength. I only mentioned that maybe Moiraine could still Morgase because the strength along could perhaps do the trick, much like Rand's fists of Spirit against the Aes Sedai.

You're more than welcome to believe that any channeler can still another one, and they merely have to duplicate that weave. I can't contest it. All I can say is that I believe that a circle offers the precision required for linked channelers to still people, and that strong channelers can duplicate this precision naturally. Strong channelers have been shown to weave precision weaves often in the series, but weaker ones almost never. As Nynaeve says, it's not about the strength as much as it is the sharpness of the shield, and when she lost it, it became a regular shield. Most channelers can probably duplicate Nynaeve's normal shield with an angreal, but very few can create the razor sharp edges seen in stilling weave. Samitsu says that she can regulate a Healing weave as well as a full circle, which shows how a circle affects channeling ability even for those who cannot Heal. Stilling people may be like 'Samitsu' but in a different domain, and when people can't do it, they link to do it. It's not a Talent, but I think precision weaving comes with strength which usually provides natural aptitude and ability with the Power.