Alert (3.5e Equipment)
From D&D Wiki
Alert: As a standard action, an alert weapon’s possessor can will it to alertness. The weapon senses any creatures within a 120 ft radius who intend harm to its possessor. Immediately, thereafter. the weapon sends forth a mental alert to friendly creatures also within 120 ft, warning them of the possible danger from the unfriendly creature or creatures. This property cannot be applied to ammunition.
Faint abjuration;CL 1; Craft Magic Arms and Armor; Market Price: +2 bonus