I’m playing an arcanist and am going to pick up Craft Magic Arms and Armor soon. I’ve been thinking about useful spells that are also common components in magic weapons, such as Fireball and Rage.
Are there any spells that cover or are part of multiple construction requirements for magic weapons/armor?
There really isn’t a small list for this... it is best to communicate with your party members about what sort of weapon/armor enchants they would be most interested in and then build a list from the spells required for those enchantments.
The ones I know of that show up across multiple enchantments however are:
Acid Arrow, Lightning Bolt, Call Lightning, Fireball, Rage, Summon Monster, Death Knell, Chill Metal, Ice Storm, Keen Edge, Heroism
You should have a good enough spellcraft skill to ignore spell PQs on crafting. The first spell I would get would be Tears to Wine, to bump my spellcraft.
Edit: some maths. At level 5, the soonest you could take the feat your take 10 total should be at least 24 (5 ranks, 3 for class skill, 4 for int mod, 2 for tears to wine.) That is sufficient for accelerated crafting speed (double daily gp progress) making a CL 9 item with one spell PQ missing.