Tekken Revolution, Ridge Racer: Driftopia, and Ace Combat: Infinity before it, the first F2P Soulcalibur will be released over PSN, and will be exclusive to the platform. Namco Europe's announcement comes after Lost Swords scans were unearthed from Weekly Famitsu (via Game Jouhou and Gematsu).
According to the Namco announcement sent to Joystiq, Lost Swords is a "free-to-play single-player experience and will feature numerous famous fighters including Siegfried and Mitsurugi." We've reached out to Namco to confirm the game features no multiplayer. Also, while the announcement is strictly for Europe, it seems likely Lost Swords will come to North America too, given a regional trademark unearthed for it a few months ago.
While details are sparse, Namco promises more info at next week's Tokyo Game Show, where we'll also get to see more of the upcoming Soul Calibur 2: HD Online.