Use a fresh blade to shave

Conventional razors cut hair by pinching the hair between the razor blade edge and the skin immediately in back of the hair. The duller the blade and the harder the hair the more force is required to cause the blade edge to penetrate the hair. The more the force applied, the more the skin behind the blade is pushed into a supporting mound. When the blade finally penetrates the hair, the blade leaps forward and shears off the skin.

The extent of this damage is a function of the applied cutting force. Depending on the toughness of your beard, change the blade somewhere between every three and every ten shaves, if you shave every day (it's different strokes for different folks, what can we say). If you're looking for a rule, two weeks is too long to go without changing blades. As to which brand of razor to use — you can't go wrong with any of the Gillette Mach series.
 

Bottom line on why you should do this:
Do you really want to shear off mounds of skin on your face?