React from my beliefsystem so be aware in case you steal anything.
To find an owl as prey and dead ( accident included) one often takes that as symbol of dead to come.
Question mostly who's number has come up and why tribe or oneself needs protection from that spirit.
That omen involved means to me that the death has been none of your doing
but needs attention anyway.
Specially since you picked it up and used it for another ritual
and decided to let war go.
Thinking about Stokastikos comment on intent...
Make a note to avoid annihilation..

Very wise.
In your intent I do however read victory over enemy and peaceful coexistence, so annihilation is out of question.
At best you played defense not attack, but your intent has been ambivalent to start with.
So reading your second sight:
That Mars did have a great slashing. It is what he does
It represents the victory part to me or mainly reversing the energy of attack.
In that he has to slice it into pieces.
If reversing energy played a role I don't feel that you can have responsibility for what they sent. In battle it is return to sender, adress unknown. Elvis is the king.
Mainly saying that this kind of defense can have this results, but only if the opponent has been stupid enough to set himself up and you had an annihilation intent.
You didn't.
So again I don't belief this to be the case here.
Owl says to me his number was up anyway....with and without your doing, doesn't matter.
Sort of makes it funny. Would you have been so upset all the time, knowing that target would disappear so fast from 3-D?
But it is still warning as I read another possibility:
If you pick up guilt or responsibility now, you may loose psychic battle
and guy can hunt you for rest of your life. Maybe he wants that. I don't know.
You become prey of owl who attacks invisible and silent instead of ally.
These kind of spirits don't give up just because they change planes of existance.
Thoughtsinfusion seems sneaky way of opponent.
The hooks maybe arrogance and power of magician.
May be you need killermoment for selfimage.
I awould say that your enchantment for peaceful coexistance did come true in a strange way.
Because that was the choice you have been making after owl, despite anger.
You don't have victory over outside- enemy... As I understand you did give up the flat, you didn't win a lawsuit yet.
However you do have a victory over yourself or enemy within.
From that I feel it just takes a short jump to banish that spirit and win final battle in other dimension.
By the way, the way you got owlfeather means it has become poweranimal of yours.
Can happen that the invisible are no longer so invisible to you.
You are a birdman anyway.
Sorry for different point of view.