This is not possible, despite patch instructions asking you to check the version of the patch files, once deployed.
The .plls, .fmbs, nor any of the Oracle source or binary objects have their version numbers embedded.
What we tend to do is keep all patches and patchsets since the base install version we applied in a hierarchy of staging folders.
If you search this folder tree for your file (e.g. on *nix : find . -name itemaster.fmb), you will find which folders this file is located in. If your naming convention for the folders is meaningful (e.g. patchset_RMS_18.104.22.168), then you can determine which is the latest patchset or once-off patch that this file is delivered. Then within the Documents->Defect Reports folder of this patchset you will find a Defect Module Xref RMS xx.x.x .xls document. This will list the version of each object within the patchset e.g. 1.12.
As WMS as the same architecture as RMS, I presume the above will also apply to WMS.
Not pretty, but it works. Once or twice it has saved us from disaster when a once-off hotfix delivered was going to reverse out an earlier fix to the same object.