A lower tensile strength means the metal has less strength or resistance to tearing apart when stretched under test conditions. It also means that these tools are softer, wear down more quickly than ordinary steel tools, and have to be dressed more frequently. All metal tools can produce sparks. Non-metals like wood, leather, and plastic are suitable for some tools like shovels, scrapers or scoops and do not pose a friction spark hazard.
All tools can ignite flammable mixtures by sparks generated by friction or impact.
This is more likely in the case of sparks formed when using a metal grinder that a spark generated when a hammer strikes some metal. Non-sparking tools are not certified for work in hazardous environments. In a hazardous environment these assurances can not be given with the use of non-sparking tools. Follow safe work procedures. Keep in mind that there are no truly non-sparking tools.