So, as the title says, I'm looking for help/information on modifying the BF pulse ray. I very much want to turn it into a keris/kris blade, to go along with my kerambits and Indonesian martial arts building in my LEGO town. As far as I know, this is the best/only solution unless the customizing gods smile down on me and answer my prayers that Brickforge makes an Indonesian weapons mold (a boy can dream, we did get ninja weapons). Any ideas on how difficult a task this would be, or if it's even possible?

I'd cut it a bit shorter and then attach a hilt from whatever sword you want... Maybe carve the end into a more triangle shape if you really want - ideally I'd sculpt an addition but it wouldn't match, obviously.

I was definitely going to cut it down a bit. But my issue, which I should have mentioned in the original post, is what appears to be the rounded "body" of the ray. I don't own one yet, so I'm going by pictures. Hence my asking. Thanks though!

I own a few Pulse Ray's and I'd have to say while the idea is great, I don't think you'd be happy with the end result. The body is indeed too round especially when compared to the "effect" that is giving off. I think you'd have more luck modifying something with a flat blade, whether it be a BF sword or the classic Lego sword. Another option to consider (which I haven't tried) would be to take some thin plastic, say from a 2 liter, and cut out the desired shape, then glue that onto a handle.

I like QB's second suggestion - plastic bottle piece. Then build up on that with green stuff or whatever. I'm now quite interested in this idea and may try this tomorrow...

You could probably sand down the round bits to the level of the wavy effect... but that might be more trouble than it is worth

Every part of this is exactly what I was thinking and why I asked.

The bottle idea, or even the modding a flat sword idea, isn't a horrible option. I'm sure I've got a LEGO sword laying about I'll never use for anything I can hack to bits.
As for the green stuff, let me know how it works out. I don't have any and have never messed with it but I'm always willing to expand my customising skill-set, especially if the results are favorable.