It sounds like a Kris Knife from the description as they have wavy blade, but without a picture it's just a guess.

Kris Knives in Indonesia were mainly ceremonial/ritualistic if I remember my art history correctly. That isn't to say that they weren't utilized as tools or weapons though, because they certainly were, but rather that the wave was more for aesthetics than functionality.

However, the blade style wasn't isolated to that area. As you mentioned, the blade is stamped Pakistan, and I've seen blades in that style in the museum from many parts of the world. Anyway, there may be other reasoning behind the wavy shape depending on area and intended use.