@bear78-- If tweezers are not aligned properly or if the ends are not filed, they will not grab hair and will become blunt after a while. I recommend slanted tweezers with hand filed ends. These are much better at grabbing hairs, they never miss.
Of course even such tweezers will lose some effectiveness after extensive use. But some manufacturers will actually sharpen them for you for free. So you should buy from a manufacturer who offers this service.