It depends on the item and which tool you want to use.

The main hand tool relates to craftsmanship, while the off hand tool relates to magic craftsmanship, this is what the devs are talking about.

If you look at you tool stats you will see the main hand tool has a higher craftsmanship and the off hand tool will have higher magic craftsmanship. In regards to that each item has an "affinity" with being crafted by either the main hand tool or the off hand tool. If an item has "affinity" with the main hand tool then the main hand tool will yield high quantity (more of the item) on HQ results, the same item that has an "affinity" with the main hand tool can yeild high quality (+!,+2,+3) ny crafting with its non-0affinity tool, in this case the off hand.

If you dont know if the item has affinity with which tool, you can make an educated guess. I will use alchemy as an example since its my highest craft. As an alchemist I use an alembic (main hand) and mortar/pestle (off hand). If I think about making glue in real life it would logically be made by an alembic, you take the materials and boil them down until left with a sticky substance, so the item has affinity with the main hand, which means that this item will produce high yield on main hand and high quality with off hand. Take the item sleeping powder, its made from belladonna leaves, logically in real life you would use a mortar/pestle to grind down the leaves until your left with a fine powder...sleeping powder, so this items affinity is with off hand tool, which means off hand tool will produce high yield, main hand will produce high quality.

This is what the devs are referring to by some items use craftsmanship and some use magic craftsmanship.

As far as choosing the right gear this girl said it well:


Quote Originally Posted by AuctionGirl View Post
Importance for all Classes (Grinding)

1) Control
2) Craftsmanship
3) Magic Craftsmanship

Without Control, you may progress quicker, but you are more often going to go unstable and then lose 30+ durability quickly if your Control is too low. Craftsmanship is what helps the progress move along quicker, too low of craftsmanship causes you not to get as many "Success 20%" but more "Success 11-13%". Magic Craftsmanship is for HQing products, the higher your Magic Craftsmanship the more "Quality" you gain per success. But remember, without Control & Craftsmanship, Magic Craftsmanship is a waste. Because unstables will quickly halve your quality on a Chaotic Explosion.

I don't think certain recipes are any easier with higher magic craftsmanship vs craftsmanship. I have done a lot of crafting and almost every crafting class is Rank 40 or above. I hope this information helps.
Hopefully that will clear some things up