An item you can trade for an improvement on your Estus Flask.
You can trade the Estus Shards for improvements on your Ashen Estus Flask / Estus Flask at the Shrine. However, you need to have the Ashen Estus Flask first or the smith won’t improve it.
Estus Flasks are essential for anyone wondering these troubled lands. The shard is still Estus soaked and even though it is shattered, it offers whoever finds it a slither of hope.