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Sun Blade: This sword is the size of a bastard sword. However, a sun blade is wielded as if it were a short sword with respect to weight and ease of use. (In other words, the weapon appears to all viewers to be a bastard sword, and deals bastard sword damage, but the wielder feels and reacts as if the weapon were a short sword.) Any individual able to use either a bastard sword or a short sword with proficiency is proficient in the use of a sun blade. Likewise, Weapon Focus and Weapon Specialization in short sword and bastard sword apply equally, but the benefits of those feats do not stack.
In normal combat, the glowing golden blade of the weapon is equal to a +2 bastard sword. Against evil creatures, its enhancement bonus is +4. Against Negative Energy Plane creatures or undead creatures, the sword deals double damage (and x3 on a critical hit instead of the usual x2).
The blade also has a special sunlight power. Once per day, the wielder can swing the blade vigorously above her head while speaking a command word. The sunblade then sheds a bright yellow radiance that is like full daylight. The radiance begins shining in a 10-foot radius around the sword wielder and extends outward at 5 feet per round for 10 rounds thereafter, to create a globe of light with a 60-foot radius. When the wielder stops swinging, the radiance fades to a dim glow that persists for another minute before disappearing entirely. All sun blades are of good alignment, and any evil creature attempting to wield one gains one negative level. The negative level remains as long as the sword is in hand and disappears when the sword is no longer wielded. This negative level never results in actual level loss, but it cannot be overcome in any way (including restoration spells) while the sword is wielded.