IMHO...glow necklaces/bracelets like you find at the dollar store, as well as the personal size glow sticks (not more than 6" in length) are totally acceptable on dark rides...as long as the kid is simply holding/wearing them and isn't swinging them around, etc. We don't allow our kids to have the lights or noises running on any of their toys on any of the rides...but seeing small children holding a glowstick in their lap or wearing a classic (read: low light) glow necklace or bracelet wouldn't bother me in the slightest.
The spinny light-up toys, lighted light sabers, brightly flashing necklaces, etc., I feel, are not acceptable. They're just too bright, and too distracting to other guests.
We bought AP's when our 3rd child was five months old. She went on all the dark rides, and the only places she acted uncomfortable were in HM when the elevator room goes dark and the screaming starts...and that tunnel in POTC (which used to be basically pitch black - this was more than 10 years ago). So, my husband would simply hit the button on his watch so that his watch light would come on (it wasn't anything obnoxious), and she would get a big grin because to her, it was like this game she played with her Daddy. He just kept his arm low, or kind of tucked against his stomach so that the light wasn't really noticeable to anyone else. It worked perfectly for us. We were there on a weekly basis until she was about 2, and I think he used the watch light for her until she was about 18 months old. After that, she was used to all the rides, lol.
All of that said....I could not BELIEVE the level of consistent inconsideration on the dark rides during our last visit (8 days in May). People were snapping SOOO many flash pictures (seriously...one guy snapped photos all the freaking way around Madame Leota's table - I wanted to strangle him, needless to say), and screaming all the time....and these were adults in their 30's and 40's....they behaved far worse than any kids with glowing things that we saw there. So, I mean....if 80% of the people in your POTC boat are talking at the tops of their voices, screaming in the dark areas, and flashing a gazillion photos....who gives a flying leap what they think of your kid's glow stick, anyway? Hopefully you'll land in groups of far less rude people, but I'm just sayin'.