The Shield Gun is a weapon in Unreal Tournament 2003 and Unreal Tournament 2004. It is one of the default weapons players spawn with, the others being the Translocator and the Assault Rifle. It replaces the Impact Hammer from UT99.
The multi-purpose shield gun serves as an offensive melee weapon, a defensive shield, and as a means (albeit painful) of extending your jump height. Hold down the primary fire button and run into an enemy to inflict a heavily damaging melee strike. It’s fun (and effective) against a sniper that doesn’t see you coming or a player currently guiding a redeemer rocket.
The shield gun’s secondary fire mode creates a shield that blocks damaging projectiles (and repels energy-based projectiles). The shield drains quickly while taking damage so don’t expect it to defend you for an extended duration. But the shield also provides another service: activate the shield during a long fall, point to the ground, and the fall won’t be quite as painful.
Finally, you can use the shield’s primary fire as a means of boosting your jumping ability. Charge the primary fire, point at the ground, and hit the jump button as you release the fire button. You can combine this technique with a running jump to reach high ledges or the top of buildings. You can also use it as a means of traversing a section of the map quickly (such as grabbing that power-up sooner or reaching the flag position faster). Note that the technique does inflict self-damage! Be healthy or, ideally, have a shield pack.