Once upon a time, in mist-shrouded days of legend, flaming swords carried by heroic figures cut a blazing swath through the ranks of those creatures fallen from favor in the eyes of the societies of the day. Swords with blades of fire were not common in those times, heard of far more often than seen. Passing years and growing scepticism (not to mention swords falling out of favor as firearms gained acceptance as the personal weapon of choice) have all but driven flaming swords into the realm of fantasy adventure movies and role-playing games.
Nonacceptance of the weapon by society and static reality aside, two major problems exist when dealing with superheated swordblades. First, the heat of the blade tends to remove the temper from the metal, leaving it wonderfully soft and malliable -- not properties most people want in a finished sword blade. Secondly, holding on to the handle of a sword radiating a considerable amount of heat isn't the most pleasant thing, particularly after the fingers of the wielder blister and char a bit.
To avoid the notice of Paradox, Foxfire relies on current passing through embedded nichrome heating elements to produce 2500 degrees of searing heat on the blade surface. An exotic ceramic/titanium alloy blade supports and protects the heating elements. Due to the inherent insulating properties of the ceramic, the blade remains insulated from the handle, while titanium in the alloy causes the heat to strengthen the blade with every use. Married to an active peizoelectric crystal edge just five molecules wide, this blade easily cuts through battlemech armor or rusted-on bolts when powered AND never needs sharpening!
Of course, owning a remarkable blade does little good if someone has taken the blade away and is in the process of discovering just how easily the former owner can be cut out of the picture. To this end, Foxfire must be dedicated to the new owner before it may be drawn from the scabbard or activated for the first time. The relatively painless process draws two points of blood from the owner, analyzing and storing the genetic pattern for future comparison. Then, prior to releasing from the scabbard for use, the handle draws a single point of blood to positively identify the user as the owner. If the blood matches the original sample the scabbard releases the blade, allowing it to be drawn and activated. Returning the sword to the sheath automatically engages the lock and deactivates the blade.
FoxFire uses 4 D-cells (batteries included!) to power the peizoelectric crystal edge and the heating elements. Prime, derived from the life-force contained in the blood of the owner, powers the low level Entropy effect which boosts damage by one (to STR+7) and helps create aggrivated (but sterile!) wounds when used against flesh. Normal battery life is about 3 hours of constant use or about two hours of intermittant use; it takes more energy to heat the blade than to maintain operating temperature. Unpowered, the blade does STR+6 damage.
In a technological society, FoxFire's effects are coincidental.