"Who taught you that?" -Yasuo

#When an enemy uses Broken Wings

• "Wait, that technique... huh." -
• "Huh, three swift strikes..." -

#When an enemy Riven uses Wind Slash

• "Another wind blade?" -
• "Who taught you that?" -

Let's look at Riven's background.

So exceptional was her passion that the High Command recognized her with a black stone rune sword forged and enchanted with Noxian sorcery. The weapon was heavier than a kite shield and nearly as broad - perfectly suited to her tastes. Soon after, she was deployed to Ionia as part of the Noxian invasion.

And

During one bitter engagement, Riven's unit became surrounded by Ionian forces. They called for support as the enemy closed in around them. What they received instead was a barrage of biochemical terror launched by Singed. Riven watched as around her Ionian and Noxian alike fell victim to an unspeakably gruesome fate. She managed to escape the bombardment, though she could not erase the memory. Counted dead by Noxus, she saw an opportunity to start anew. She shattered her sword, severing ties with the past, and wandered in self-imposed exile - on a quest to seek atonement and a way to save the pure Noxian vision in which she believed.

Now the question is, what powers does the rune blade have?

The Runic Blade Passive, Ki Burst, and and possibly Shield are all tied to the runic energy by description.

• Who created this runic sword, or stole it?
• Are all of Riven's abilities tied into the sword, or were they taught by someone else (if so likely in her exile)?
• Some suspect that Riven killed Yasuo's master, but if this is true was it during the war, or was it in her exile and WHY?