I have a diamond nozzle installed already.

PETG's issue in this particular application is layer strength, wherein it's difficult to top PLA except with some semi-exotic and rather hard to print materials like polycarbonate. Both the screws and the blade carrier in my design rely on layer adhesion not failing for durability. Otherwise honestly the parts are all pretty low stress other than I guess potentially the pocket clip.

I got really good results with CC3D GID PETG and a steel nozzle.

For a short time in total darkness it actually is pretty bright. Obviously my phone's camera automatically wound the exposure up quite I bit when I took that picture in the dark, though. That was without any special charge-up, just an hour or so of exposure to the largely LED based lighting in my office with it lying face up on my desk.

This is the Overture brand glow PLA.

I whacked it with my little Lumintop single AA flashlight last night and left it sitting on my bedstand, and found that it was still quite visibly (albeit dimly) glowing by dawn the next morning.

From a chemical composition standpoint I couldn't tell you, but my off-the-cuff testing indicates that the glow remains visible for quite a few hours -- All night, in fact, though obviously tailing off in brightness considerably as time goes on.

It's interesting to hear that there is a new style as I've done several prints using the old style and it's so lame that it only works for a few minutes after being exposed directly to bright light especially with how rough it is on the machine. It wore a groove through the hotend on my old Sidewinder X2 after using about a Kg to print a giant Lego skeleton.

Ask the Filipinos, who are the ones who both invented and named it. "Butterfly knife" is a western neologism for it.