The Maguindanao also had heavy blades. What moves it more in that direction for me than Maranao are the fittings. Filigree and woven silver are more of a Sulu style/expertise and good chased okir work more of a Maranao style/expertise. According to Cato, there was an influence of Sulu style that could be seen in Maguindanao and not so much on Maranao. The mixing of the two influences is more of a Maguindanao trait. These are the reasons I lean toward Maguindanao.
On the swaasa question, swaasa is a mixture of gold and other metals to attain different colors. This was not only used in the Philippines, but also in Indonesia and Malaysia. The most common metals mixed with gold were copper and silver. Most of the swaasa that I have seen (and with a friend made) is made with a larger portion of copper and smaller amount of gold. This combonation creates an orange color to the metal at a roughly 7-9 karat gold. A second semi-common form I have seen has a larger amount of silver and lesser amount of gold (same karat) and this changes the color to a bleached gold look. The orange variety was probably more affordable to make, though still quite expensive. I was wondering if the band on top of the pommel is gold layer over silver, brass, or swaasa in a variation of the orange color.
Below is a picture of a Maguindanao kris I got in eBay years ago made with ivory, silver, and swaasa done in okir design. It is my avatar, but I thought the larger picture would be easier to see (and much more delightful
). The swaasa is the orange colored okir bands on the hilt. On the pictures of the whole thing, the slender bands are the swaasa that a friend and I made to match those on the hilt (this was the second scabbard I made from scratch, including the okir silver band work).