Grappling typically requires at least one free hand; Ranar has a shield in one hand and pickhammer in the other.
Getting close and bashing knees is certainly a viable plan, though. If you’re keen on the grapple idea, though, you might try to hook a knee with your hammer:
That is a bit of a finesse move, though; it’s tricky to successfully pull off, and Ranar isn’t really a finesse kind of fighter.
