I've often seen hammers dismissed as mediocre or worthless in online discussions of this game. Just like in Dragon Quest VIII, they seemingly play second fiddle to axes (which in turn, are inferior to Falcon Blades). Their physical damage skills like Heart Breaker and Bagsy Last leave a lot to be desired. Conversley, their "ultimate" skills, Crackerwhack and Big Banga, cost so much MP that your Gladiator will never actually be able to use them.

All of this is true- IF you conceptualise hammers as a weapon for physical bruisers. However, in my time spent obsessively replaying this game recently, I've come to the conclusion that hammers have an incredibly legitimate niche. If you put them on spellcasters with a lot of MP to burn, they're honestly broken.

Crackerwhack costs a mere 12 MP to use, and deals 160-190 damage to all enemies. Big Banga costs 16 MP, and deals 240-360 damage. You can access these skills as soon as you have 100 skill points to allocate (so level 38 without seeds) and complete the relevant quests. Comparatively, Kaboom isn't learned by Mages until Level 47, and has a cap of a mere 218 damage. Only the very strongest spells, Kacrackle and Kaboomle, can reach higher omni-target damage than Big Banga, and they cost an outrageous 50 and 56 MP, respectively.

Most high-damage spells and abilities also rely on your stats in some way to reach their highest damage ranges. Gigagash, Lightning Storm, and Solar Flair all use Strength, Magical Might and Magical Mending in their calculations, so you won't be reaching full potency with them right off the bat. Not so with Big Banga. You'll be doing obscene damage from day one.

Additionally, the fact that you only need to use hammers for these techniques, and aren't using them for bonking enemies directly, means that it doesn't really matter how strong the hammer you're using is. Big Banga hits just as hard when used with an Oaken Club. This means that you never need to upgrade your hammer, which saves a ton of money and alchemy resources.

So in short, hammers provide some of the cheapest and most easily-available monster-clearing capabilities in the game. Put them on a Mage, Priest, or Sage, equip the free Goddess Ring you get from the Observatory, and you'll have enough MP to end most random encounters in the game in seconds. Doubly so once you get the 25% MP reduction from Enlightenment. This remains useful far into the postgame, which you can't say about most weapons not called "swords" in DQIX.

The only thing holding hammers back is that none of the vocations with abundant MP can wield hammers by default, and thus it can be awkward to pick up Omnivocational Hammer Master. Without grinding, you'll either have to make your spellcaster save up points until level 38, or take a bit of a weird route like Mage > Gladiator > Mage, which can leave them a little underlevelled. But the end reward is SO worth it. When my Sage goes first, she ends fights in a single turn.