[kmonster]

The game usually lets you keep one special weapon or armor piece per character, by having only one item equipped you can enforce keeping it (unless it's one that never transfers).

After importing your character stats are reduced a little randomly, the level is reduced to 5.
Miss chance is raised by 3 (max 100) for every level higher than 5 your character was independent of class. So samurais or ninjas who got it reduced by 3-6 per level up (and other fighting classes who got it reduced by 2-5) in W6 often start with better miss chance than possible for level 5 and casters like bishops who only got it reduced by 1-3 have a worse miss chance.
Miss chance is also subtracted for high levels although characters don't get miss chance reduction after level 21, so if you level a character higher in W6 he'll have worse miss chance at the start of W7.
You can improve your W7 starting miss chance a lot if you switch classes at the end of W6 and level up to level 5 before exporting. But keep in mind that switched level 5 characters have far worse attributes than created level 20 ones.

When thinking about how to export best into W7 the regeneration rate is most important, it's set at the start of W7 and never changed afterwards. You can see the regeneration rates in my previous post.
If you start W7 as mage with 17 piety and vitality you'll regenerate much faster than if you start as fighter with only 13 piety and vitality even if you switch both to samurai for for example.
Attributes are reduced on transfer, but higher is better nevertheless. Higher W6 stats grant a better chance for higher W7 starting stats and therefore higher spell regeneration.

Weapons definitely worth importing are the samurai sword and the valkyrie lance.