Grubberfly's Elegy

Description
''Contains the gratitude of grubs who will move to the next stage of their lives. Imbues weapons with a holy strength.''

When the bearer is at full health, they will fire beams of white-hot energy from their nail.

How to Acquire
Gifted by Grubfather after freeing all 40 Grubs.

Charm Interactions

 * With Fury of the Fallen equipped, the player will fire red projectiles when at 1 HP. Because Fury of the Fallen increases Nail damage by x1.5, the projectiles now do 0.75 x Nail damage per hit.
 * The range of the projectiles is not affected by either Longnail nor Mark of Pride.

Usefulness
For the amount of work recquired to obtain this charm, it can be a little lackluster. While a quick mid-ranged attack can be convenient, it only deals half of your nail damage and the ability will be lost if you recieve damage. Not only that but the beams of light will not generate soul upon landing, which will make healing even harder. that being said, it synergizes very well with Quick Slash for sending out more nail beams, Fragile Strength for increading their power, as well as Lifeblood Heart and Lifeblood Core, which allows you to take 2 to 4 hits before losing the charm's ability.

However, Grubberfly's Elegy will not synergize with Joni's Blessing, as you will still be unable to shoot the light beams with it if you take any damage.

With all these things considered, it is best to use this charm on exploration areas and change it to something else for boss battles, unless you don't have difficulty dodging most boss attacks, in which case the extra range can prove to be quite useful.

Trivia

 * The beams of energy are likely a reference to The Legend of Zelda. In multiple installments of the series, the main character Link can fire ranged attacks from their sword, but in most games to feature this he can only do so when his health is full.
 * After all of the Grubs are freed and this charm is obtained, resting at a bench and visiting the room again will reveal that the Grubfather has eaten all of his children. The name of the charm, Grubberfly's Elegy, could be foreshadowing this, since an "elegy" is typically a poem mourning the dead.
 * However, many fans theorize that the Grubfather is actually protecting his children by serving as a cocoon for them to metamorphose. This is possibly supported by the description of the charm and the name of the achievement for rescuing the Grubs, "Metamorphosis". In that optic, the "Elegy" could be for the Grubfather, since upon completing their transformation his children will presumably burst out of him, killing him.
 * This is further enforced by the fact that a "Grubberfly" is a creature never seen in the game, and so is most likely the imago stage of the Grubs, with the Grubfather's consumption being the pupal stage.