This is definitely a weak point of WOT, once it's infiltrated you have to get rid of the attacker another way. We've actually had "petnames" for as long as I've been around, the problem with them is people aren't likely to assign them unless people's own names are confusing to them. Adding petnames publicly also has some privacy implications which would make them hard to share.
#askNostr,
As we should all know, it's pretty trivial for a Nostr user to change their profile name and picture. I think this is a good thing (maybe couldn't stop it even if we wanted to). However, it seems like this ability could be gamed to help facilitate impersonators in a way that could evade most detection: e.g. if an nPub I'm already following decided to impersonate another nPub I'm already following, I don't think I would notice.
Obviously, this would require a much longer game by a would-be impersonator than the issue nostr:npub1jlrs53pkdfjnts29kveljul2sm0actt6n8dxrrzqcersttvcuv3qdjynqn is addressing in his note I've quoted here; but, the solution to this long-game impersonator might be pretty simple: Nicknames (a la, what the Signal app uses). If every entry in your follow list also had a 'Nickname' field, it could easily be used to always display the nPubs name that was used at the time you chose to follow that nPub; or even whatever Nickname you chose to assign to that nPub. Maybe clients could allow you to toggle between displaying the nPub's chosen name, or whatever nickname you've chosen for the nPub, or perhaps both simultaneously.
At this point, I'm just rambling; and this doesn't currently seem to be a big issue; but whenever I notice someone who I follow has changed their profile name otherwise unannounced, something in the back of my mind is tells me this presents a potential danger that could be hard to detect.
Discussion
The privacy issue hadn't occurred to me; but, I see now how someone could inadvertently (or intentionally) dox you through your "petname"... that could be a problem.
As far as usage goes, maybe the standard client action could be to populate the nickname to match the display name at the time of being added to a follow list... if that nickname never got changed from that point on, so be it.
Some clients do this, it's not a bad idea
Gossip client lets you override somebody's name with a petname, and puts a special symbol next to their name if you did that. Pet names were supposed to be a distributed naming web where you would refer to somebody through somebody else's petname: JudgeHardcase.hodlbod would be the person that hodlbod calls "JudgeHardcase". But I never coded anything like that.
Regarding the privacy issue, this might be a stupid idea, so I won't hold it against you if you just ignore it. 😉
When I choose to follow someone, add a nickname initially populated with that user's display name - but encrypted by my nPub (requiring my nsec to decrypt). Then, clients could indicate to me when the encrypted version of that user's display name no longer matches the saved nickname... and, if I wanted, I could choose to have the nickname updated to stay current with the new encrypted version of that user's display name. (though maybe simply 'saved_name' would be a more accurate description than either 'nickname' or 'petname').
... or maybe even just save some sort of hash of the display name so that a change can easily be detected (and subsequently update the saved hash if and when I verify it's okay to do so).