WebEx Players gives users the option to re-save ARF recordings to WRF format. This can be done using the File ► Save as.. function in the program. Unfortunately, this seems to be the only way to achieve the arf to wrf conversion.
As far as we know, no 3rd party allows for this type of conversion, so using WebEx software is likely your only available option to convert arf to wrf.
Updated: October 12, 2022