Two years ago, I replaced my incandescent stern light with a waterproof, sealed LED unit from OGM (www.miseagroup.com). This winter, while the boat was on the hard, I noticed that the seal had failed and drops of water fogged the lens. Although the LED continued to work, I was concerned that the moisture would reduce the visibility, or that the light would fail when I needed it most.
If you're going to sail you'll be doing some stitching-no two ways about it. That doesn't mean you have to go overboard with sail repair tools. Don't jump into the $100 do-everything kit. Start with a modest kit, adding tools and materials only as your skills grow and projects require them. Chances are, you already have most of what you need in your other supply lockers or tool boxes.