Question about Finger Seal and Incantation scaling

[Bo]

I don't know why some numbers won't scale as expected. I'm a dual wilding heavy build (vigor, endurance, strength, faith). I did a test with one weapon:

• Weapon: Heavy Claymore +16
  
• Seal: Finger Seal +8
  
• Spell: Flame Grant me Strength
  
• Ash of War: Royal Knight Resolve
  
• Affinity: Heavy

My base damage (R1, R2, R3) is: 465, 197, 140. When i'm casting the spell the damage raises to: 558, 236, 168. So far so good. Now i upgraded the Finger Seal with a Smithing Stone from +8 to +9. But when i now cast the Flame Grant me Strength spell, the buffed damage of the sword stays the same: 558, 236, 168.

I thought uprading the seal would make the Incantations sort of "more powerful". What am i missing here?

[Bo]

Ok, did some reading. It appears only specific seal buff specific incantations. So for Flame Grant me Strength i would have to use and level up the Giant's seal? So this leads me to another question. What sense does is make to level up the Finger Seal? According to some wiki, this seal doesn't buff any incatation category.

[Indure]

The spell you are referring to, as well as almost every other "buff" spell gives a flat bonus. It might be possible to gain additional bonuses from specific seals that say they do it in their item description, but just smithing a seal won't change a buff. The scaling is there to effect the damage of faith spells.

[Veezora]

Some specific seals buff certain spells MORE, but buffs if I recall have specific percentages and don't increase based om scaling. So Flame, Grant me Strength will always be something like a 20% increase, regardless of what level your seal is.

Where you will see the difference is with damaging spells, such as the fireballs, which would then get an ADDITIONAL boost if you used the Giants Seal, due to being a flame and damaging Incantation.