How do I determine if my puppy is sharp?

Sharpness, in my opinion, is the tendency to be reactive to stimuli. In the dogs I have experience with seeing from birth to adulthood, the dogs that tend to be sharp and have natural aggression as adults may actually show shy or aloof behavior as pups. Many times they are the pups that get their hair up quickly, bark a little bit too much in response to a new person or situation, or actually appear a bit lacking in self confidence in certain situations. Being patient and having an understanding of young dog development is the key to nurturing a dog like this properly.

NOTE...this is where you need to know your bloodlines and know the different phases pups go through on their way to adulthood. Handled incorrectly, these dogs can grow up to be either very nervous (if unjustly corrected for showing these behaviors)or complete monsters (if inappropriately rewarded at the wrong time).

There are MANY pups that show all the things I listed above who simply have poor nerves, but the pups I have experience with go through phases as they grow up that if misunderstood can ruin the dog.