Magnesium chloride deicers, rather than the typical rock salt, are less harsh on a wood surface. Magnesium chloride works just as well as rock salt but is less corrosive. It may be more expensive than rock salt, but it will not damage the wood balcony finish. Magnesium chloride works until temperatures reach minus 13 degrees.
When shoveling show off your wood balcony, it is best to use a plastic shovel rather than metal. Plastic will not dig into the wood as metal would. In really tough spots with a lot of ice buildup, use a plastic chisel rather than a metal chisel.
Ashes from a fireplace is an old-fashioned solution to deice a wood surface. Ashes can add critical traction to the surface during ice and snow events. Ashes should be swept up after the ice and snow is cleared away.
Although not ideal, cat litter or sand will make the surface somewhat less slick until you can get a deicer on the wood balcony. Spread it around the icy wood balcony much like you would a deicer. Be sure to sweep the litter or sand off of your wood balcony.