image of a example when he royal guards compared to gunslinger this style will be light blue

This is a very important part so read carefuly you will need to lock onto Dante and use the Devil Bringer if all goes well it should look like this

Once he tried to block the Devil Bringer and failed you can activate Devil Trigger (optional) and let go of lock on and use the Devil Bringer again and if you did it all right it should be like this

Now enjoy stopping Dante from royal guarding