The Opponent deals 1 wound and has Killing strike. Does negation by sacrificing armor / shield cause that the Opponent cannot spend 2 momentum on the second wound? Will it be the same for Intense Quality?
I’d say yes. The wound is prevented in the first instance, so leveraging it for additional damage wouldn’t work.
Mostly I’d do this from a cinematic POV. Mostly Sacrificing Armour / Shield is something that PCs or boss characters will do, so giving them another round before the wounds start stacking up and making everything harder feels right.
Because Killing Strike is “if you inflict a Wound, pay to inflict another” (paraphrased), it’s conditional, and thus negating the initial wound prevents the option to inflict an extra one.
Other instances of inflicting multiple wounds in a single attack - such as Intense or simply dealing both 5+ damage and reducing a target to 0 Vigor inflict all the wounds simultaneously, so sacrificing armour or a shield would stop one wound, but not all of them.
Intense is also conditional:
If an Intense attack inflicts one or more Harms upon the target, then it inflicts one additional Harm
It uses almost the same construction as Killing Blow.
So following your logic then sacrificial armour prevents the first Wound from being inflicted:
The damage breaks the armor or shield, instead of inflicting the Wound.
Whereas simultaneously reducing a target to 0 Stress and doing 5 or more damage separately inflicts a Wound from each cause, so sacrificing armour would only prevent one of the Wounds.