The Emblam of Pentagram is the highest +dam item available for the 'on arms' position. It is usable by any non-neutral character. This item is carried by the Lord of the Air, also know as Satan, in the Air Citidel.
This is what identify reveals about this item:
Object 'emblem pentagram' is type armor, extra flags hum dark invis magic anti-neutral.
Weight is 2, value is 5555, level is 97.
Armor class is 5.
Worn:Takeable Arms
Affects damage roll by 8.
Affects hp by 50.