°trackballer

newRot = hand.rot * heldRot * spinRot
if (offCon.triggerBtn.held && held != null)
  newDelta = Inverse(newRot) * offHand.rotDelta
  newDelta *= newRot
  spinDelta = Slerp(
    spinDelta,
    newDelta,
    Time.deltaTime / 0.1f
  )
  
spinRot *= spinDelta

// lower the speed the higher the friction
friction = 1 - Clamp01(
  Angular(spinDelta).magnitude / deltaTime / 15
)
friction = friction * friction * friction;
spinDelta = Slerp(
  Quaternion.identity,
  spinDelta,
  1 - (friction * Time.deltaTime)
)
heldRotDelta = newRot * Inverse(oldRot)

held.rot = hand.rot * heldRot * spinRot
// or
held.angularVel = Angular(heldRotDelta) / deltaTime