Hi,
It is not possible to set the severity field in the Trap Details from the agent. But from the manager, using the Trap Parser Editor you can try setting the severities. Trap Viewer parses the file created using the Trap Parser editor, with the help of the TrapParserBean, to match each incoming traps with certain criterion.
Kindly refer to the following section in the Help Documentation for more details :
Tools -> MIB Browser -> Parsing Traps
Thanks,
Devi.