@Ijerk: Impractical? As a ranged weapon, yes, but it looks like an effective close range melee-based weapon.

But what I was thinking is like a handheld gun weapon that fires a single stream similar to the tools that use water to cut metal.

@Chameloshi: Similar to the one used in this video , but toned down with less pressure so it would still have range without wasting ludicrous amounts of liquid nitrogen.

It doesn't need to cut things, just freeze 'em.