How to filter only those docs that have not been signed?

I've only seen this feature if you go online to the Document Cloud or  in Adobe Acrobat Pro DC  if you've shared documents for signature via Adobe Sign.

You also need to be online or the status of all your agreements won't show at all.

See slide below:

I've been trying for the longest time to find something similar but you won't get it in the "Home View".

Even though you can run a similar script (like shown below) from the console (with the appropriate arguments , of course),  as a mouse-up action event in a button, or using a javascript action through the action wizard,  I personally have not found a way to perform this from Acrobat against a list of files that are saved in a folder (which are also dependent on the operating system in use and its file system structure, in addition to privileged context issues) and be able to  determine which  documents are encrypted with the Acrobat's default security handler:

console.println(this.securityHandler != null ?
"This document is encrypted with " + this.securityHandler
+ " security." : "This document is unencrypted.");

In any case, I've came up  with a little batch script which is handy for this purpose. I posted it sometime last year in another thread but no one seemed to care at the time. Maybe you'll find it very useful:

@Echo Off
echo(
echo(
echo ----------------------------------------------------------------------------------------
echo(                         
date /T
echo(
assoc.pdf
echo(
echo ----------------------------------------------------------------------------------------
echo                    Total PDF(s) found in the current directory
echo ----------------------------------------------------------------------------------------
echo(
attrib.exe ./*.pdf | find /c /v  "" 

echo(

dir /D /B /P /O *.pdf 
echo(

echo(
echo ----------------------------------------------------------------------------------------
echo             Total Signed PDFs , Encrypted or Password protected PDF(s)  
echo ----------------------------------------------------------------------------------------
echo(

setlocal
Findstr /M "adbe.pkcs7.detached" *.pdf | find /V /C ""
Findstr /M "Encrypt" *.pdf | find /V /C ""
echo(

Findstr /M "adbe.pkcs7.detached" *.pdf

echo(
echo ----------------------------------------------------------------------------------------

echo          Some Password Protected file(s) MAY NOT open for reading/printing.
echo          You can separate these PDFs from the source list by placing 
echo          them in a different folder

echo ----------------------------------------------------------------------------------------
echo(
echo The listed PDFs will be copied now to a separate folder. 
echo(
echo Hit the "Ctrl"+"C" keys to exit batch job at any time or

pause

echo(

mkdir C:\Users\--\Desktop\TEST
for /f %%a in ('findstr /M "adbe.pkcs7.detached" *.pdf') do XCOPY /Y "%%a" C:\Users\--\Desktop\TEST\NEWTEST
for /f %%a in ('findstr /M "Encrypt" *.pdf') do XCOPY /Y "%%a" C:\Users\--\Desktop\TEST\NEWTEST

echo(
echo(
echo ADOBE ACROBAT WILL OPEN NOW
echo(

pause

for /f %%i in ('START ACROBAT.EXE') do START %%i 

You can modify it to your needs. It is a text file so you can copy from here, name it,  and save it as a .bat file with Notepad (or similar). 

Note : This script  runs from the current directory where you place it. In my example above I created a user folder in my Desktop name "TEST" , for example. When it finds the encrypted or signed document(s) in that folder it copies the found files to another folder named "NEWTEST" . This is to allow to work on them separately and individually without messing  up the originals.

All this script does is count and list how many PDFs are in that folder with the attribute string "adbe.pkcs7.detached" or "Encrypt".

If files are found a total count will appear in the second row as illustrated in my screenshot below, if not found a "0" will show.