Arc Browser by "The Browser Company"

PopClip Extensions
3

In mean time this ought to do it, just needs Arc’s bundle ID put in there:

#popclip
name: Open in Arc
icon: A
requirements: [url]
javascript: |
  popclip.openUrl(popclip.input.data.urls[0], { app: 'INSERT ARC BUNDLE ID HERE' })

(The above block is an extension snippet - select it to install the extension with PopClip)