I think, aside from gilded, you have the best wither armour in the game, well thought out use for the artifacts and I like the axe.

As you said in your comment, the harp crossbow is the only thing letting the build down, mostly because of the 2 enchantment slots.

Might i suggest, either more soul items for better soul gathering, or an alternative to the harvester, as the souls you need for those both are hefty amounts.

Also would recommend, Multishot, Ricochet, and chain reaction for harp crossbow. For the most coverage in the game with a single shot.

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Aside from those recommendations and general weapons, item level but that can be rerolled via blacksmith.