I'd suggest a Nightstar ( www.shakelight.com ) or equivalent cheaper "Forever Flashlight" (ebay) for a child that young. Attractions:

1) Too big to swallow, big enough to not get lost as easily as a smaller light
2) Completely sealed, NO removable parts to eat or lose
3) No consumables (i.e. no bulb, batteries or chemicals). LED light powered by shaking the light up and down. It lasts pretty much forever. Shaking it to make it light up will also amuse the kid.

One danger: it has a powerful permanent magnet inside as part of the power generator. Don't let it near your credit cards.