Rapier's aren't "bad", but they're not really "good" either. I feel they should have more range, but sadly they don't. The longest ones struggle to match basic longsword range, seemingly attack at the same speed, but they deal less damage, and require more stat points. The only saving grace is counter attacks seem do deal 15% more damage across all weapons. Thrust damage deals a bit more, as during attack animations thrust defences are reduced by 30%. The damage bonus stacks multiplicatively with the Leo Ring which gives a 15% bonus, meaning you should get counter pokes that deal 133% damage and are 30% less resisted (in practical terms against sl.125 player, 30% less thrust defences is about 5-9% more damage).