I'm sorry, but what exactly is an onion slicer? Is this a particular type of kitchen gadget? It sounds interesting.
I have a lot of trouble with my eyes watering around onions too. And, no matter how much I wash my hands afterwards, if I handle an onion too much, I can have a lot of trouble taking my contacts out. Ouch, if you know what I mean.
So, I always use my food processor to slice or chop onions.
But, thanks, Everyone for all the tips above. I'll try some of those...