Just a thought, but last I checked there's basically a dot or something dividing Aerondight from replica in the name for Grøh's weapon when translated on the JP site. So while it's a minor additional consideration and he specifically says "Roar, Aerondight!" during one of his moves[can't recall which gameplay it was I caught that], there's a chance that Aerondight could be his weapon as one of the blades, most likely the one more closely matching the armor on his left arm, and the opposite is just a replica of some sort forged for the purpose of combining for his overall weapon/style. Sure, no way to be certain for now, but it's not an unreasonable theory. That aside, the Arthurian Tales being a coincidence would be quite surprising, given how much easily points to it.
No idea if the Aval Organization's other weapons have been mentioned so far aside from maybe Grøh's Aerondight, though there's a small chance the altered lore could be something along the lines of it being a 3rd sword somehow closely tied to Soul Calibur and Soul Edge, and something along the lines of "long kept secret/hidden from history" or whatever the case may be. But I'd doubt that unless we see evidence, personally.
Ling Sheng Su has Krita-Yuga[Xianghua's Soul Calibur], Dvapara-Yuga[the mirror now worn on Kilik], and Kilik's Kali-Yuga staff.
On a side note considering the idea of 3 weapons in a set of sorts, if the Aval Organization has their own 3, we have 2 more to consider. Ling Sheng Su has their set. We have Soul Calibur and Soul Edge, but aside from possibly just keeping it for cosmetic purposes in SCIV, anyone think you could maybe consider Irkalla, Zasalamel's scythe from when he was Abyss, could be the 3rd for that? Nothing really pointing towards that, but it and the Abyss form was caused by him trying to use the swords to die in 3, so that could be a thing if they decided to go that route in this or a future game. Seems to just kinda have been there in 4, but it would be interesting if they did that eventually with it.