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You can go perpendicular as long as the direction of the spin is away from the edge and not into the edge. Be VERY careful about this and even then you'll ruin about 1 blade in 10.

Unless you go with more aggressive abrasives (like flap wheels), you should be fine. Dremel felt pads should make your life a lot easier either using Maas or the Dremel red polishing compound.

Some pics might be useful in making that determination.