Before the latest seeker update where lightly armored scaling was removed, I could see the signature weapon +1 bonus in blue on my character sheet whenever I'd one hand a shortsword
Now that's not there and I'm not getting that in the examination of my weapon or on the character sheet before, when not a week ago they both worked.
To test yourself compare a lvl 24 rogue build with a single shortsword with a 24 seeker / 3 rogue build using the same.