Name of rhetorical device

[IceQube]

What's the rhetorical device called for flattering one's opponent?

Here is an example of flattering one's opponent (bolded):

There will always be likelihood of confusion as to the source or sponsorship of the goods, and the use by such prominent companies would dilute the distinctiveness of the trade slogan ...

[njtt]

Does it need a name apart from flattery (which is, after all, inherently a rhetorical device)?

Incidentally, it is hard to be sure without more context, but it seems to me that what is said in your example might well be perfectly sincere. Use by prominent companies would dilute a trade slogan much more than use by obscure ones.

[Trinopus]

And prominence is not always complimentary. Jesse James was a prominent Missouri citizen!