Contrary to popular belief, a blackguard is not a fallen paladin. He or she is a a holy knight that has chosen to uphold the code and creeds of an evil God rather than those of a good. Blackguards are lawful evil and can be as honorable and as moralistic as any paladin -- they just have a different code of conduct as per the evil God they worship.
They, like their good-aligned analogs, the paladins, are hearty fighters that possess limited magical powers. These powers are granted to them by their evil deities and are used to further advance their vile causes.
Blackguards gain a 20% bonus to hit while wielding a 2 handed weapon.