The attached plugin should do what you want. If not then let me know.
Note: This plugin requires TF2Attributes. Here's a link:
https://forums.alliedmods.net/showthread.php?t=210221
Console Variables:
sm_diamondback_allplayers_enabled : Will show you if plugin is enabled or disabled
sm_diamondback_allplayers_enabled 0 : (default) Disables plugin
sm_diamondback_allplayers_enabled 1 : Enables plugin for all Human players
Admin Commands:
sm_dbrocketson : Gives YOU Diamondback Rockets
sm_dbrocketsoff : Removes YOUR Diamondback Rockets
sm_dbrocketson <target> : Gives target player(s) Diamondback Rockets
sm_dbrocktsoff <target> : Removes Diamondback Rockets from target player(s)
Command Examples:
sm_dbrocketson steve : Gives player named Steve Diamondback Rockets
sm_dbrocketson @red : Gives all human players on RED team Diamondback Rockets