In regards to the thread starter's original question-
Best Quality,longest lasting screwdrivers I've found are Snap On-pricy,but they will fit and grip screws that others will strip out. When they show signs of wearing out,my SO driver replaces the shank and I'm good to go.
Second best but less costly IMHO is Klein-they're available in the electrical department in Home Depot and Lowes and at most electrical supply stores. Warranty is tougher-the guy in the store makes the determination if something is warrantee-able or not,and they're not too inclined to help you out most of the time. If they warranty something and Klein disagrees,the store takes the hit.
As far as buying and warrantying broken tools,I feel that the warranty has been bought and paid for by the original buyer and should be honored regardless of who now owns the tool,but I understand that SO has a new policy that can require you to show the original reciept for the purchase from SO when you try to get it repaired or replaced...