Hi Miguel:
Your
dha sword no. 1 has a fairly high hilt:blade length ratio and some nice silver work that is probably Shan in origin. I would put this one as late 19th/early 20th C. Shan or northern Thai.
Dha sword no. 2 again has a fairly high hilt:blade length ratio and is probably northern Thai/Lao in origin. Early 20th C.
Knife no. 1 with lots of silver is typical Shan work. Probably mid-20th C. or a little earlier.
Knife no. 2 with the ivory hilt is Burmese and probably late 19th C.
As far as references for
dha, I have not found a good reference in 20+ years of looking. There are bits and pieces in books that deal with a wide range of material culture from mainland SE Asia, but nothing comprehensive on
dha that I have come across. There is the
article and
pictures from the History of Steel Exhibition, and the
Dha Index that Mark Bowditch put together, which has a
small bibliography
Ian.