I've used a lot of cinnamon on some plants, Gigi. Never had it burn the leaves at all, in fact I used it on a small black spot that I just cut out of a Catt leaf, dumped it thick on all the cut edges and it healed up really well.
Patty suggested mixing the cinnamon with some Elmer's glue and painting it on the cut areas to keep it in place, and from washing off in the rain.
I do think you need to leave those Vandas outside, not keep bringing them in the house where it's a lot cooler and drier. It's probably ok to do that in the spring and fall when the difference in temperature and humidity isn't so much, but at this time of year, that change is a shock to the plant.
