Michel, Rick & drdavid are correct that the angle of the keris is physicall biomechanic purpose. To understand this, you will have to understand how the keris is used for combat. In Malay martial tradition, when fighting using a keris, you are not to parry your opponent's weapon, but instead you side step to the especially left, or right. When stabbing your opponent from the left or right side, the angle will suddenly make sense.....
Philosophically, the downward angle also represents humbleness, the general character of the Malay people....humble but deadly
