particle
you know; I tell you; emphatic sentence ending
Sentence-final casual particle that adds light force, confidence, or punch to a statement. It is familiar and often stereotypically masculine or rough, so it can sound inappropriate in polite or formal situations.
この店のカレーはうまいぜ。
The curry at this place is really good, I tell you.
明日は早く出るぜ。
I'm leaving early tomorrow, you know.
particle
threatening sentence ending; ironic sentence ending; heh
At the end of a sentence, ぜ can make the speaker sound threatening, taunting, or ironically amused. The tone depends strongly on context and intonation.
今度邪魔したら、ただじゃおかないぜ。
If you get in my way again, you won't get away with it.
よく言うぜ、昨日も遅刻したくせに。
You've got some nerve saying that, after being late yesterday too.