Is there are way to filter for the items that upgrade on harbinger kill?

As the topic says. Is there a good way to make these items show up?

For reasons I would like to collect some of these, but I forget to collect them without a loot filter showing them to me.

So far only way to make them show up is to set up for each weapon type their own rule. Is this really the only/best way to do it?
It would just add quite a few lines of rules to my filter for mere curiosity.

As far as I’m aware, that is the only method currently for it. The loot filter doesn’t have implicit affix search, which would be the proper way to do it.

I would suggest you add your vote to this thread:

Maybe also add your own comment. to keep the thread alive and so devs are aware of it.