I've very little to add to Ian's excellent post.
As Ian notes, the silver sheeting and decorative wirework is distinctive and is often seen accompanied by ivory handles. Paul and Elaine Lewis ("Peoples of the Golden Triangle", Thames and Hudson, Ltd., 1984) also attribute these silver knives (and, indeed, the similar silver swords) to ethnic Chinese and Shan craftsmen.
These weapons are probably valued as trade items, as they are evident in photographs of various other hilltribesmen, including the Kachin.
I've handled many of these, and the quality runs the spectrum. Some knives are spectacularly decorated with pierced and intricately carved ivory handles, and some are more pedestrian. The blades also vary greatly, with some sporting folded or laminate construction, and others demonstrating quite crude manufacturing.
Guy, in my opinion, your example is a fairly average example of the style, and I would agree with Ian's assessment of age. Cool knife.
