What two words, added together, contain the most letters?

I'm unique, one of a kind, Yet often ignored, just left behind, Rarely sought, till there's distress, Maybe you'll find, who made this mess

I vanish when you need me most, then show up where I shouldn’t be. I get blamed when nothing changes- but you’re the one sitting on me.

I’m wielded by hands but not for crafting art. One form tills the soil, while the other may break hearts. What am I?

I wear a cap but have no head, I sleep in earth, my leafy bed. Though small and round, I hold great might one day I'll grow to touch the light.