Block a specific URL that only ends with a specific keyword

Your requirement is not quite clear.

Do you actually need to block URLs with specific keywords like "Logon" or just any URLs which don't have any parameters?

If you just need to block the URL without parameters you can simply make the parameters mandatory on wildcard URLs:

"*/Logon" 
"*/Logon/login"

and block if mandatory parameters are missing (e.g. parameter named "service" as per your example)

Another way is to create a custom ASM signature - refer to SOL15241:

https://support.f5.com/kb/en-us/solutions/public/15000/200/sol15241.html

Hope this helps, Sam