All of the threads I found were referring me to the Enterprise Deployment Guide, which provides little assistance on this issue except in the case of HA mis-configuration. Typically, My Oracle Support was a salad of unrelated material.
The problem, in my case, turned out to be a dependency issue. I determined this by navigating to $ORACLE_HOME/soa/thirdparty/edifecs/XEngine/bin, and running the following:
$ ldd libxejni.so
This returned numerous instances of:
libstdc++.so.5 => not found
Since we're running OEL 6.5, the solution in my case was to yum install compat-libstdc++-33.