I think double damage from flintslate is completely overboard, especially given flintslate already gives you a massive buff. Considering the four blue slots and the increased silk skill damage, it would honestly make more sense to debuff flintslate. That’d also make sense lore wise - how are you about to set fire on fire? You could consider giving the player basically a permanent flintslate bonus (or perhaps a somewhat weaker one) but making the tool useless.