My code is a little messy (one day of jam and such) but it goes like this:

• Player Script:
  • private void Update() {
         if (!dead) {
              handleAim();
         }
    }
    void handleAim() {
         Vector3 mousePos = Mouse.current.position.ReadValue();
         Vector3 Worldpos = Camera.main.ScreenToWorldPoint(mousePos);
         weapon.Aim(Worldpos);
    }

• Weapon Script:
  • private void Update() { UpdateAim(); }
    public virtual void Aim(Vector3 mousePos) {
         aimDirection = mousePos - transform.position;
         aimDirection.z = 0;
         aimDirection = aimDirection.normalized;
    }
    public void UpdateAim() {
         Vector3 currentAimDirection = transform.up;
         currentAimDirection.z = 0;
         currentAimDirection = currentAimDirection.normalized;
         Vector3 rightDirection = transform.right;
         rightDirection.z = 0;
         rightDirection = rightDirection.normalized;
         Debug.DrawRay(transform.position, aimDirection, Color.blue, 0.1f);
         Debug.DrawRay(transform.position, currentAimDirection, Color.red, 0.1f);
         float rotationDirection = Vector3.Dot(rightDirection, aimDirection);
         float angularVelocity = -Mathf.Sign(rotationDirection);
         float maxAngle = Vector3.Angle(currentAimDirection, aimDirection);
         float rotationValue = angularVelocity * rotationSpeed * Time.deltaTime;
         rotationValue = Mathf.Sign(rotationValue) * Mathf.Clamp(Mathf.Abs(rotationValue), 0, maxAngle);
         transform.Rotate(0, 0, rotationValue);
    }