Thank you for adding a "signature" button to VE :-)
I'm not sure when this was done, but it's the first time I've noticed it!
Currently, or at least where I just used it on https://www.wikidata.org/wiki/Wikidata:Property_proposal/Creative_work ,
the button is found under the "insert" and then at the bottom of the "more" option in the editing toolbar.
I'd like to propose that in cases where the editing is happening:
A) on a Talkpage
B) where that Talkpage is not "Flow" enabled
that the "your signature" button be made much more prominent. For example, moving it to the main area of the toolbar, next to the Omega symbol for different characters.
I'm not sure if it is technically possible to make the VE editor layout different depending on where it is being displayed, but I figure that since "adding four tildes" is something that every editor needs to do almost every single time they visit a non-Flow talkpage, this is a feature that WILL be used a lot. Far more frequently than "add a bullet point list" or "different characters" features which both get their own top-level buttons on the VE toolbar.