The oldest samurai sword ever found is difficult to determine definitively as the term "samurai sword" typically refers to the curved katana, which emerged during the medieval period in Japan.

However, there are earlier examples of swords associated with samurai or their predecessors. Here are a couple of notable examples:

1. Chokuto Swords: Chokuto swords were straight, double-edged swords that predate the curved katana. These swords were used in ancient Japan, particularly during the Kofun period (3rd to 7th century CE). While not specifically "samurai swords," they were used by warriors of that time and are considered precursors to the development of later Japanese swords.
2. Tachi Swords: Tachi swords were the primary swords used by samurai during the Heian period (794-1185). They featured a curved blade and were typically worn suspended from the samurai's waist, with the cutting edge facing downward. Some surviving tachi swords from this period are considered among the oldest examples associated with samurai.

It is important to note that the designation of a specific sword as a "samurai sword" often refers to the curved katana that emerged during the medieval period. The earliest surviving katana swords typically date back to the Kamakura period (1185-1333) or later.

While there are earlier swords associated with warriors in Japan, the specific age and origins of the oldest samurai sword ever found can be challenging to determine due to the passage of time and the scarcity of well-preserved ancient swords. Archaeological discoveries and historical records continue to contribute to our understanding of the earliest swords used by samurai in Japan.