Valiant Knife is a mid-ranked dagger that can only be used by Locke. It has an attack power of 145, +10% Evasion, and enables the Runic command. It can be found in Kohlingen in the World of Ruin. It is a unique and powerful weapon in that it deals more damage the lower Locke's HP is, it ignores the enemy's Defense stat, and ignores the penalty of the Master's Scroll relic. It is also unique in that only one exists, making it a valuable weapon, and it cannot be Thrown.
The Valiant Knife is a level 69 dagger with decidedly mediocre damage of 24 and delay 195, but with a hidden effect of dealing increasing bonus damage as the user's HP drops. At less than 1% of maximum HP, it is the best dagger in its level range, but surviving in such a state is likely to be difficult at best. It drops off the Notorious MonsterLindwurm in Ifrit's Cauldron.