Basically there's three reasons for using aftershave.
First, it acts as an anti-septic to prevent cuts from becoming infected wounds. But if you're shaving and constantly cutting yourself, aftershave isn't your biggest concern.
Secondly, it smells nice.
Thirdly, and possibly most importantly, it acts as a moisturizer. Our aftershave has moisturizing properties to keep your skin hydrated. Its hard to overstate the importance of moisturizing. Properly hydrated skin is easier to shave, looks healthier, and is less prone to itchiness and irritation.