He had made many mistakes.

Fighting the mafia family on their own turf was the least of them. Fighting them on their own terms was worse.
Not thinking they would bring 2 PIAT's, in addition to the Tommy guns, that was the biggest error.
The two missles hit the ground at his feet, and he was blown to smithereenes.

The sword flew from his hand, for a split second it hit the floor, it 'clanged' once, and then the ground opened up before it, and down the blade fell.

The ground closed up behind the blade, and a fresh rupture opened up before it, bright red blade, long sword in size, flamberge is style, with a one handed onyx black hilt, down and down it fell. Earth flew past at 9.8 meters per second per second, until the cavern upened up.
For a few moments it dropped through the dank air, then the tip of the blade hit a rock. There was a sound, a 'shhinnnnng', and then, all was quiet.

There was no light down here, just a big dank cavern, deep underground. In the middle of the cavern, surrounded by still water and almost alien algae, a rock, and protruding from the rock, a sword. The cavern has a few exits, and a few reach to the upper world.
A cave diver could be lost for decades, before they ever found this place, unless they get lucky.....
Very very lucky.
It is said the blade has a will of its own.

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Will You be the one to claim the Blade of the Underworld.
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Powers
(CoX) Longsword / WillPower

*Tank / Brute / Scrapper*

RPG (game terms).
1) The blade ignores most defences, even forece fields and armor, it can be countered by reflexes/agility style dodges. Since it passes through defences (essensially, it ignores material strength), it can cause greivous/aggrivated wounds with ease.
2) The blade empowers the weilders willpower, and through will, enhances the users damage resistance, regeneration, and defence against mental attacks. It may also leave the user feeling over-confident as to the extent of their defences.