You see the ability specifies that you should not get m atk if you don't hold a rapier as the buff is not meant to be received with alternative weapons but is to be benefitted for compensating the lack of m atk in rapiers. it being viable on other weapons makes empower staves and acumen maces the only way to go for Soul Hounds
In the images the difference between no buff and buff. Also you see I got a magical staff.