Hello there! Don't worry your situation is perfectly normal. You will need to have at least 1 Tuvala Ore in your inventory in order to see the exchange option at a blacksmith.  I'm not certain what your other question is, but if you respond with the quest you are working on or perhaps rephrase I can help further. :)

To reword this, I am trying to do [Manor] Crucio Domongatt's Summon quest, and it says " You must meet a certain requirment to obtain the knowledge of this NPC. There is a hint for obtaining this knowledge withing the quest of Heidel's tale."

I don't have relevant black spirit quests available nor I can see any relevenat quests in quest journal for this

Some knowledge entries are only obtained via different crossroads. There is an indicator when you reach a crossroad to let you know how many times you have completed a crossroad. While I can't be 100% sure given the details you have provided I have a very strong inclination to believe that you may have to complete a different crossroad in order to get the knowlegde you seek. Please note that in order to do a different crossroad you must progress through the quests on a character that has yet to do them. If you pick the simplified questline to skip the quest progression you will not be able to perform any crossroad selection in the Balenos (Velia), Serendia (Heidel), Calpheon and Mediah (Altinova) main quests.