the Keris Panjang may very well have been used predominately as a ceremonial weapon, yet the construction, at least of the one I have, is one of a true weapon (as many western ceremonial weapons too have ) with a fuller running in the center ( with two consequent risers to give rigidity) almost the whole length of the blade and a forte with a long sogokan to strengthen the blade where it matters for use that may support at least some slashing intentions. Did I mention that the blade appears to be hardened? The legend of the execution is supported by very few accounts and it doesn't take a great anatomist to see that a 35cm blade would be more than apt to pierce the heart from the shoulder collar bone , so, making mine a 65cm blade is , quite literally, an overkill!
True the tang, the pesi, won't be long and wide enough though. to support much slashing .
This is my Panjang. It came with a king fisher hilt which I don't think it is the proper one and so I am replacing it (see other thread on the Pattani hilts on panjangs).
about videos, there are many silat video's displaying fighting techniques on you tube, it is always possible that some would show Panjang use.
on you tube you can also see videos from Malay makers and you see how condiderably simpler the construction of more modern Panjang is let alone the fact that the modern ones seem often to show pamor which the older ones don't have
https://www.youtube.com/watch?v=cAqdWEHhvV4
https://www.youtube.com/watch?v=DlEesFQyamg&t=747s