When new, your poodle face blade #40 or #30 works fine for carefully scooping out matted pads, but after sharpening, they nick the skin. Two or three different things can cause this problem. The most likely thing is that the blade-set is not properly re-assembled. The cutter is either too close, or extended beyond the leading edge of the comb. This will cause the back and forth motion of the cutter to cut the skin. If the blades are worn, then this will happen, even using the correct sharpening equipment. The sharpener should tell you when the blades are worn-out.
Another reason may be that your sharpener may not be using the proper equipment. Some grinders are still using the old flat table that requires them to hold the blade on the circular table by hand while it is turning. If he puts too much pressure (some pressure is required to hold the blade on the table) on the leading edge of the blade, then this edge will grind down to a sharp edge, which will cut your finger.
Metal blades are cast from a mixture of iron and carbon, usually containing between 0.2 and 1.5 percent carbon, often with other constituents such as manganese, chromium, nickel, molybdenum, copper, tungsten, cobalt, or silicon, depending on the desired alloy properties. The more carbon used in the manufacturing process, the harder the steel. The harder the steel, the less sharpening the blades need, but the more brittle the teeth will be when dropped.
Ideally, blade manufacturers will opt for a metal that falls somewhere in the middle for their blades. The metal should be soft enough that it does not readily break when dropped or does not lose a tooth on a dirty coat, yet be hard enough to withstand the use of constant cutting. However, these dull quicker than blades made from the hardest steel. The Oster Elite Cryotech blades and the LAUBE CX are very hard and will stay sharp longer, but they are also more brittle.
I would recommend shampooing the dog BEFORE grooming, whenever possible, as sand in the coat could damage the blade.