Here's a link to a disputed study regarding Tlingit knife making. Keep in mind the Copper River is a huge source.
http://www.penn.museum/documents/pub...Metallurgy.pdf
While this thread starts out with a Tlingit /Haida Shakats, it has examples of varied design changes.
http://www.vikingsword.com/vb/showthread.php?t=13961 Oh, The double Double bladed type called shakáts, a type of “combat knife” that swung a blade both directions, unless it was used to do the actual “slave killing” along with the “ceremonial blade” then it was known as goox du een (with the slave). : Keet Gwálaa (Killer Whale Dagger) used in “ceremonial killings but never in “combat" See photo. The culture saw slaves as wealth and it is not clear to Me where ceremony ends and actual killings took place for tribal status.
Steve