I'm not saying that you should just "let go" of those unspoken arguments. Pick the battles that you are prepared and adequately skilled to see through on your own. For instance, if you have experience to glean from or a particular specialty in an area, then by all means proceed with the argument with gentleness. Although I can't speak for all of us, I can admit that I only have one or two realms of which I feel adequately prepared (to be able to move the other person based on my character and experience) to argue on my own.
A bunch of years back, I had a conflict that although I was clearly being wronged and clearly in the right, I knew I was not going to "win" this battle. So, for as much as I can remember, I kept my mouth shut and endured until the matter was brought to court. And, without throwing the person under the proverbial bus, I merely answered the judge's question honestly.
What ensued was the victory that anyone but that judge would not have been able to deliver for me. Although I was not particularly smart for that age, something in me said to keep quiet and wait. I learned that on my own, I would have blown my "argument", but when the right "judge" (which was literal for this real life example) came along- I was delivered relief and justice.
So ladies and gentlemen, don't just shut up about it-- stay in your clean character, continue to love and to bless; but DO pray and do have faith that if not now, then later is a better time. I can't tell you exactly when. If it truly is a small matter, and the better "stakes" don't come around- then ask God to break this angst from your body, spirit and mind. It might even come to a point, if it is a large enough conflict, that you might have to break soul ties especially if that person is deceased. None but the power of God can break toxic soul ties.
The benefit to choosing your battles, is that with prayer you don't have to do it alone; you don't have to fight of your own power, energy and strength. You can invoke the wisdom, truth, and love of our Supreme God to fight on your behalf. Or at least call on God to purify your heart and spirit when you cannot come to a resolution with that person or issue. Ultimately, seek resolution in prayer or in gentle argument.
Funny enough, I am in a smaller scale situation as the first, and without argument- the person is making amends. And I didn't have to say a word... With God on our side, do we even need to speak? =)
Blessings to all of you...