Form Verification/Assess Security Risk action still points to the old
Sitecore.Form.Submit.AssessSecurityRisk which is marked
Obsolete messages are marked with "Please use X instead"...
Given that the out of the box
Assess Security Risk Action is still using the obsolete class you are probably ok to continue to use this for the moment (until the next upgrade at least). I would still raise a support ticket and ask for clarification though.
In Sitecore 8.2 the
Assess Security Risk item has no
Assembly items set, which suggests the item has been left in as a legacy for existing forms but is no longer used. It may be that the form submissions are encoded by default now, but worth verifying with Support.
The verification was removed in WFFM 2.4 rev 151103, which would have been rolled into the later WFFM versions.
The default Assess Security Risk verification had worked incorrectly for the list fields. This verification can now be removed from the form. (66912)