Many of the OperServ commands are listed in the OperServ help files however they are issued with different services agents such as NickServ or ChanServ, the reason why they are listed under OperServ is because you need OperServ access to issue these commands. OperServ access levels are Services Administrator also referred to as SA, ChanServ Super Op aka CSop, and root administrator.

DROP - Drop a registered nick.
INFO - Show info on a registered nick.
GETPASS - Show the password for a registered nick.
LIST - List nicknames that match a selected value.
MARK - Set a nickname so that it can't be getpassed or setpassed.
SETPASS - Set the password for a registered nick.
UNIDENTIFY - Make nickserv forget your identification to a nickname.
WIPE - Delete all access list entries for a registered nick.

/msg nickserv getpass Mark