Users connecting to salesforce using weblogic will have to do one of the
1. Disable Host Name Checking.
2. Upgrade to Weblogic 10.3.6+ and use the "Wildcarded Host Name Verifier"
3. Configure a custom host name verifier:
Hope this helps.
Have you imported Salesforce Certificates at runtime & also setup CSF Key? You probably need to increase the runtime loggers to TRACE:32 and reproduce the issue to identify the problem
Disabling Host Name checking worked for me.