Published on Organic Gardening (http://www.organicgardening.com)
A few swipes with a fine file may be sufficient for a quick touch-up of pruning shears. With one hand, hold the shears flat against a work surface; position the file at the same angle as the cutting edge's bevel.
Links:
[1] http://www.organicgardening.com/sharpening-pruners-8-380