Hilt markings on horseman's sword

[urbanspaceman]

This is a horseman's sword with a 1688 blade from Shotley Bridge.
I suspect, at some point much later, part of the hilt has been replaced with what looks like a munitions grade shell and knuckle guard… and possibly a grip binding (copper).
The pommel feels original.
Can anyone identify any of the markings:
either on the shell CA (I?) M and IV / 2;
and/or the details on the pommel?