One thing to remember is that in battle the keris blades were often laced with frog poison so even a small cut would result in death whether it be from a stabbing or slashing movement.
“The dagger, called Cris ('keris') a blade measuring 2 palms in length, is made of fine steel; it bears a deadly poison”
http://www.sabrizain.demon.co.uk/malaya/johor3.htm
"The blade is like a snake in mid-strike. In the old days, the blade would be dipped in poison to assure certain death with the slightest stab",
http://www.nikhef.nl/~tonvr/keris/ke...ay_kris03.html