More than 20+ unique Phantom Edges are confirmed. The official Steam page also states that they can be acquired from defeated foes.
Phantom Edges: what is published
Confirmed count
More than 20+ unique Phantom Edges
Published acquisition
Acquired from defeated foes
Related content
Part of the same combat system as primary weapons and action mechanics
Why Phantom Edges have their own guide
The official description presents Phantom Edges as unique items and specifies a defeated-foe acquisition path. That makes them a confirmed combat-progression topic separate from primary weapons. Together with primary weapons and published defensive actions, they form the currently confirmed combat-system picture.
Source note
Phantom Edge counts and the defeated-foe acquisition statement come from the Steam store page linked directly by S-GAME; the image and trailer come from official S-GAME channels.