by the taper, you are increasing the bonding area, without increasing the width. your taper diagonally, would break no matter how good the solder joint. you would be putting all the cutting pressure on the joint closest to the blade teeth. when that cuts into material, it would break worse than original joint. plus, heat rises. you would have to put the angle straight up to get a proper weld joint. one of the few things i've learned watching my friend weld is that.