Item: Dawnblade the Shortsword:

Arindell, a goblin character belonging to one of the male playtesters a little bit back managed to find a few magic items for sale from a traveling trader and after a bit of negotiating for one item and leaving, came back in secrecy.  She fought the trader for the rest, rendering him temporarily paralyzed as the character used a teleportation device to get out of the situation.  Then came a lot of fire and other wasted attempts trying to see whether the trader was merely hiding or nearby somehow and once satisfied she looted the caravan.  More on those other items later, but one contained a sprite that she freed, and they became allies.  She also tried to free and befriend a instinctive shadowpup which turned a mouse into a skeleton in an instant before she managed to keep it at bay with a bright light.  The sprite, who called himself Drexel, chose to bind the shadowpup to Arindell's shortsword.  After Arindell experimenting with it a little bit, Drexel said it needed a name.  One was chosen, Dawnblade.  Their adventures continue, but let's visit Dawnblade for a bit:

Item: Dawnblade the Shortsword (2 lbs) (90 GP) (10 Toughness) (25 EP) (Bound Creature, Shadow):
     This shortsword has a shadow-pup bound to it by sprite magic.  As a result, it reaches out at foes to try to pull them closer to it when not within one movement square of a bright light or in an area with no shadows due to overall brightness.  When jabbing outside those areas, it gets +1 Physical Damage on success, plus +1 Shadow Damage.  When swinging outside those areas, it gets +2 Physical Damage on success, plus +1 Shadow Damage.  If a creature or character is weak against shadow damage, this bonus is cumulative to their weakness.  If they are neutral to it, it is just the +1.  If they are strong to it, they take no damage from the shadow damage.  If they are powered by it, they gain +1 HP from the shadow damage.  Once per battle in which it has drawn blood, Dawnblade may recover 1 EP.  The blade itself disappears into the hilt when the lighting is over-saturated in a movement square or if next to a light source, rendering it useless outside its scabbard in these instances, but it may be used as a Simple Club in these situations.  Repair of Dawnblade is special as a bound creature weapon.  It requires insertion of a new blade, which the shadowpup will consume and form when drawn, and a half-pint of blood to be coated on said new blade.  It cannot be rebuffed or refurbished on the blade itself, as the heat and grinding will cause harm to the shadowpup.  It is recommended to do this before its endurance reduces to 0, as the shadowpup will die as well as the blade being shattered.