Charles Saunders may also be able to add a great deal about these as I recall he has some great examples
Well as I said above all I know has mostly been added. This is called a piso podang by stone and von Zonneveld , The curved ones are referred to by Gardner as "pedang shamshir" ( G. B. Gardner in KERIS AND OTHER MALAY WEAPONS). Piso may be a variant of the word pisau , and podang peudeung and pedang certainly have similar roots ( in my mind at least ) .
With Piso Podang the hilt is usually cast in one piece where the hilt of many tulwar are cast in two pieces and joined . They are known to have local blades, indian blades, european blades and even rarely wootz blades. These swords (Piso Podang) are most commanly found amongst the Batak in Sumatra. However, there are appearantly some references that do show Iban Dayak carrying Piso Podang. It should be noted that the Batak are non-islamic( Actually Batak is a general name for 6 groups with different cultural and linguistic characteristics, but they believe in a descent of a common ancestor) , and most references to them do not tell of their origin but do talk of the Hindu and Chinese influence. It is believed this sword form came through the Hindu influence as noted above
Some links on it
http://blade.japet.com/Pedang-Podang.htm
http://old.blades.free.fr/swords/pedang_sab/ped08.htm
Some other pictures of these
http://www.oriental-arms.co.il/item.php?id=960
There are variants of the hilt
http://img13.photobucket.com/albums/...d/pisohilt.jpg