can iWatch silence a paired iPhone?

Hi

No - whilst it is possible to enable mirroring between your devices for Do Not Disturb mode, Silent Mode settings cannot be mirrored between your Apple Watch and iPhone.

Silent Mode instead needs to enabled and disabled separately on each device.

More information:

https://help.apple.com/watch/#/apd62807a9f3

If you enable do not disturb on your watch and have the settings correctly you can silence both your phone and Watch.

In the watch app on your phone go to settings/general/do not disturb, then select mirror my iPhone

As I hoped to explain, Silent Mode is a different feature than Do Not Disturb mode.

Silent Mode cannot be mirrored between the watch and iPhone.