What does a spell going “haywire” mean

If you tithe enough pieces, you get an artifact you can use or sell.

From the wiki:

Each Lutefisk tithed increases the chance of receiving a random reward (each Lutefisk increases the chance of obtaining an artifact by 0.2%, up to 100%).

You can sell to the shopkeeper three ways:

1. Click on the item in your inventory and then drop it onto him.
2. Click on the item in your inventory and then drop it onto an available space in the shop.
3. Hold down shift while in a shop to enable quick-sell mode. Then click on the item in your inventory. It will be sold immediately without telling you how much you will get or confirming the sale, so be careful.

Any non damage modifiers on weapons(ranged or melee and even shields) apply to the character, regardless of what attack you decide to use.

If your axe skill increases a non-damage related skill(critical chance is damage related skill), it will apply to your character.

So yes, abilities you gain from items and skills that arent damage modifiers, but other bonuses, will apply to all attacks.