Head flail overpowered?

It is powerful, but it lacks versatility, as it can only attack forward. the cost is also among the highest in the game.

Each shard works differently, like the burst gale shard travels along the ground and hits multiple enemies. The straight arrow shard that, when upgraded, becomes a room clearing shotgun that reaches several screens away. The throw axe, while short range hits multiple times. The summons have unique characteristics, like the Gieremund running back and forth over an area, while the ghost will track enemies.

Granted, a number of the shards seem underwhelming at first, but do not count them out. Some are elemental in nature, owing to certain weakness we have yet to be able to exploit.

It was strong enough to cream almost every enemy unupgraded in my playthrough. Which is a bit too powerful for an early game power.

In general I don't feel the demo has the best balancing. Some options are really too strong for early game, even if unupgraded.

Because the thing is: in this kind of game raw damage outclasses a lot of things. So even if it's not versatile or elementally aligned it still has an advantage in the early game. The cost doesn't stop it as it is relatively mild and mana regenerates pretty quickly here.

What you mean it can't be upgraded? I upgraded it to rank 4, although I think the shard upgrade system is not in place yet, because nothing seems to change.

This Shard actually can hit close enemies behind you, too, if I recall right from my play-through--sort of like Christopher's whip in The Adventure Rebirth. That said, it is overpowered and probably needs to take up more MP. However, I like it, and I think the Dullahammer Shard should have an upgrade where you can spin it like a shield over your head or in front of your body when you hold down the Shard button--something like Nathan's whip twirl in Circle of the Moon or the Hammer Joe in Mega Man 3.

Exactly this! Just like the demon itself does, adding some delay would make it much more balanced and in line with its origin.

Yes it can, it saved me sometimes killing monsters behind me!