AFAIK Topaz pads are certificate-based. For digital (certifcate-based) signatures in Acrobat DC you need to you Certificates tool, not Fill&Sign, which is for hand-written/images signatures (e-signatures). Acrobat 9 had only digital signatures, so you most likely need to use Certificates tool, which works the same way as the "Sign" menu item in Acrobat 9 (with additional functionality added since then).
This reply did not address my fundamental requirement to sign after launching Acrobat from within an Internet Explorer browser window.
The "Sign" menu in Acrobat 9 was available when launching Acrobat in IE. AFAIK the "Certificates" tool is not available -- nor is the "Sign" tool -- when launching in IE browser window.
Does anybody have a solution, or is this a case where Adobe removed critical Acrobat functionality and did not provide equivalent or better support in their latest version of Acrobat Pro DC??
Ooops, It looks like Acrobat DC functionality in the browser is limited compared to the desktop Acrobat and I do not know why. I will try to get more info on this. Can you sign using your pad in the standalone (desktop) Acrobat?