Old Larger Indonesian(?) Kriss Dagger for Comment

[blackinaz]

I've had 2 Kriss daggers for years and decided to see what if anything I might be able to find out about them. This post is for the larger one. Another post for the smaller one will follow.
This particular dagger measures 20 inches long with the sheath and approximately 18 inches without the sheath from the top (pommel?) to tip of blade.

The top of the sheath (wood portion) is approximately 6 inches wide.

The widest part of the blade at the top is approximately 3.5 inches wide and 1/2 inch (.5) in depth.

The carved wooden handle (pommel?) is approximately 4.5 inches long, 1 inch wide (from the front with carving facing out) and 1.75 inches in depth (from the side).

How does one go about determining the age?

I'd appreciate any information or direction I might receive from fellow sword/dagger enthusiasts.