No, you will be rewarded with the blade once the quest is completed, however, when Sir Prysin gives you the blade, you can drop it and then receive a second one from him. Otherwise, if you do happen to lose Silverlight, you can buy another copy of the blade from Sir Prysin for 500 gp. The same goes for the Darklight Blade, although that price goes up to 1000 gp. The only blade you will not be able to buy is the Arclight Blade, which is made from an upgraded Darklight blade. Keeping Silverlight or even mounting it in your home player is a great way to keep the sword handy. Especially since you will need it for the final fight of the 'Shadow Of The Storm' quest line. Silverlight is whenever you dye Silverlight black for the 'Shadow Of The Storm' quest. This will consume all the copies of the sword in your inventory, leaving you with just the dyed sword, so make sure you have an extra copy outside of your inventory becomes the Darklight blade).