With the exception of some breath weapons, all weapons have an attack type. There are two attack types: blunt and edged. Edged can be further broken down into based on the distribution of the blade into "true" edged attacks and piercing attacks.
Some weapons can have more than one attack: a short sword has a slash, a stab, and a pommel strike.
Examples of blunt weapons include hammers, maces, and melee attacks with crossbows.
Blunt weapons generally have poor penetration but are good for bruising and breaking internal bones and tissues. Blunt weapons tend to be more effective when they have greater weight. This can lead to disappointment when using blunt weapons made from awesome materials. They are not designed to kill, but to incapacitate, and they do that very well.
Examples of edged weapons include heavy bladed weapons where the focus of the swing is generally distributed across a long, thin blade. Bladed weapons include axes, swords, and even scourges.
Edged weapons do significant amounts of tissue damage and may sever limbs or heads, especially of smaller, weaker creatures. Against large creatures they cut gashes in the surface tissue, causing bleeding and pain but generally not doing a lot of organ damage, unless the strike is to the head, of course.
Examples of piercing weapons include any weapon that focuses a significant amount of energy on a single point. Piercing weapons include spears, bolts & arrows, and some sword attacks.
Piercing weapons are perhaps the most effective at killing large creatures due to the penetration required to hit vital organs. It doesn't take an extremely lucky strike with a spear to puncture a lung or other organ, although hits to the limbs will be largely ineffective because piercing weapons aren't designed to break bones or cause deep lacerations. It's possible (although unlikely) to kill even a megabeast in one hit with a spear or pike (unless the megabeast in question is made of fun substances).