Crowbar (DX)

In Deus Ex and Deus Ex: Invisible War, the crowbar is a melee weapon.

It's usually found in industrial areas, such as in elevator shafts or near power generators. Gunther Hermann seems to show an affinity for crowbars, as seen on a note in the crowbar's description in Deus Ex. The first one in Deus Ex is found at the Liberty Island dock, next to some crates.

Strategies
In Deus Ex, the crowbar is useful for destroying crates before you get a combat knife. Once you get a combat knife, dump the crowbar because the knife does a very similar amount of damage and it only takes up one space in the inventory, compared to the crowbar's two. The crowbar also has a slower swing time compared to the Combat Knife, yet only does slightly more damage.

In Deus Ex: Invisible War, the crowbar is merely a slight upgrade to the combat knife. If you're using the baton or have the energy blade, don't bother. Otherwise, you should pick it up, if only to make destroying crates a little bit easier.

In-game Description
A crowbar. Hit someone or something with it. Repeat.

 Many crowbars we call "murder of crowbars." Always have one for kombat. Ha. -- Gunther Hermann 

Trivia

 * The Crowbar is actually a direct reference to the one in Half Life, Gordon Freeman's first weapon. Its use here is identical - break open crates, remove obstacles and bludgeon approaching enemies.

Łom (DX) Łom (DXIW)