Harvest

Harvest is the ancestral sword of House Darry, made of Valyrian steel. It is a bastard (hand and a half) sword made of the metal which has been owned by the family intermittently for over a thousand years. Its current owner is Lady Amerei Darry, but her husband Ser Clement Hayford is its current wielder.

Meta
(yup, the only house in the Riverlands in AWOIAFRP with a VS sword is House Darry of all people)

Harvest was one of 18 entries to AWOIAFRP 3.1's Valyrian Steel Writing Competition, being selected by the moderation team as their winner after failing to accrue enough support to win the popular vote. The full entry can be found here. 

Description
Harvest is a Valyrian steel sword, constructed for House Darry during the 740's BC. The sword is a bastard sword, with a straight and uncarved blade designed not for any kind of finery; the very sword itself is enough, the only one known in the Riverlands. The grey rippled blade was forged for one purpose, that purpose being to kill any and all who oppose the Darry holding the weapon. The pommel is also a circle of Valyrian steel with a small lead core to provide the proper balance with the lighter metal.

The grip itself does not contain the jewels and precious metals of other swords. It is plain even for an older sword, with a grip made of the softest leather, the grip shaped to fit the current owner's hand and changed for a new one upon their death. The blade is light enough due to its metal to be held in one hand by even a half-decent warrior, while it can be used in two hands even by minors or women.

History
(As detailed by Amerei Darry in her scrolls on the subject, written 415-416 AC)

It has been said that seven hundred and fifty years before the First Conquest, House Darry reached its zenith, or at the very least the height of its power before the Conquest. We had risen high in House Teague's esteem through our loyalty and riches had been heaped upon us as a result, including our first stone hall. Yet even with such a thing, Lord Addam Darry desired something to show his house's power, something to show our power to all. And so he sent three hundred loyal men and half the Darry treasury to the topless towers of Valyria, to the forges of the dragon lords. Their goal was to bring back what at the time would have been one of only a couple dozen in Westeros; a sword made of Valyrian steel.

The sword produced would be plain, almost mediocre compared to some of the other swords that have been found in recent years both in Westeros and abroad. I have no shame in admitting we could not have afforded the rubies and gold that adorn more ostentatious pieces but such plainness would prove to be not a curse but a boon. The sword they could afford was a bastard sword, made almost entirely of the metal but for a leather grip that was torn off and replaced with each new wielder, the current grip being customized for Clement's hand after Harvest 's rediscovery.

The plainness of the sword makes it easy to hide when it must be carried covertly, the weapon appearing like any other upon a brief visual inspection as most lackluster guards are wont to do. This also makes the sword lighter, so light that for proper balance the pommel is rumoured to have a lead core. This makes the sword even lighter than most sword of its type, enabling a talented fighter such as my husband to dance through his enemies with a speed that a heavily ornamented sword could not to hope, even if it too was made of the same metal. This also enables less talented fencers such as myself (see Table 14 for further comparisons) to use it more effectively than a normal sword, as the weight is low enough even an unfit user can swing it safely with two hands.

A Sword Lost (739 BC - 282 AC)
Lord Addam died as men do, bequeathing the sword to his daughter Bellena, who would be the first recorded user of the sword in a small skirmish against the Storm King's forces. While of course the sword did not make its user invulnerable, it made them a force to be reckoned with, able to cut through armour with a single stroke.

Upon its return Lord Addam would die and it would pass to his daughter, the Lady Bellena. As time passed and wars became more frequent with the stormlords and later ironborn the sword proved its mettle time and time again, doing the best it could to defend Darry from its assailants even if that was often an impossible task. Frequently the lord was a minor or the male line was extinguished entirely, and thanks to the foresight of its makers Harvest was still able to be used under dire circumstances by these rulers with great efficiency.