I've been part of a international group of competition historical combat using Rattan weapons. i'm vaguely assuming the sabers would hit lighter (we dent 12 Gauge steel helms with some of our hits). But there is a massive amount of variation with armor from Gothic full plate, samurai armor, late period "hidden" armor etc. but all with the same armor requirments (which officials check EVERY tourney or war) here is the basics which i know might not be relivant with sabers but something to think about. Full helm with front grill or slots 1/4" smaller then the min weapon thickness, rigid over the elbows, knees. Full wrist/hand protection, Groin protections for both males and females, rigid over Kidneys, throat/upper spine guard. Any armor other then that is pure optional though shoulder/collarbone armor is very common.
I think the key two points would be to have concerns over face/eyes, and throat.. Hand hits might not be "dangerous", but since i'm just healing from a broken pinky finger from fighting a young pup using my short polearm, i can say they might still need some attention.

(he got my pinky through full steel gauntlets when i blocked.. but i caught him up side the head at the same time) Guess my points would be protection is very critical, BUT you can do it with quite a bit of variation for looks (they also have modern sport/combat armor just for this sort of thing that can be worn under cloths/gear.
That all being said.. Just recently found out about these LED Sabers, and am soo hooked... my wife not quite so happy.. but even at 5 my daughter wants to be a sith with a rainbow saber...?? Not sure if there are many others over here in Maine, but my best friend and i think we can convert quite a few of our fighting friends over to sabers too