Actually, funny thing, the weapons in Castlevania don't just simply have their own hitbox. They're entirely different seperate sprites to the character him/herself. In other words, they use method number 2. I use this method myself, and I find it's generally very reliable.
And, on the plus side, you can simply re-use animations for certain weapons. Take Castlevania: Dawn of Sorrow, for instance. Soma has attacking animations for particular types of weapons, no animations for specific weapons, the only exceptions being the pistol and the RPG launcher. Soma's animation for lighter weapons such as a knife or a short sword, for instance, is a quick one-handed forward strike. His animation for heavy weapons is a two-handed overhead swing. And one of the neat things about these re-used animations, is, that the animation speed varies depending on the weapon's weight, if I remember correctly. "Lighter" heavy weapons he will swing quicker than heavier ones.
But, yeah, I reccomend using separate sprites for the weapons, it's a common technique, and it's practically the best one for dealing with many weapons.