Thankyou for the poking guys. I forgot all about this thread, mostly because the root question that I posed overflows into so many various aspects of living that I was finding it difficult to put it all down without going off on tangents. 

 But I will do my best.
I want to say firstly that I entirely agree with your post, Elanor. It was very well said, and all the points about speaking death or life into a person by the words we say, I absolutely agree with. So what I am about to say can be taken as additional, not contrary to what you shared.
Lady Elanor Mimetes wrote:
If people chose to go around sowing death in their words, tearing down, spreading lies, then I believe that the scripture in Proverbs means that they will reap what they are sowing. Same as if someone builds up, encourages, nourishes, pastors and quickens, they will reap what they are sowing, which is life!
I especially agree with you here. Just thought I'd note that. 

To begin, I believe the words we speak have power in themselves. In most cases though, a careless word does not have any force behind it because the speaker lacks conviction. (i.e. a sarcastic comment)
NKJV wrote:
For assuredly, I say to you, whoever says to this mountain, 'Be removed and be cast into the sea,' and does not doubt in his heart, but believes that those things he says will be done, he will have whatever he says. [emphasis mine]
But I don’t think that if one simply believes in what they are saying they will get it. What you said about demanding things like prosperity or money and expecting to get it, I don’t believe in to a certain extent. I believe in order for you to gain from the words you speak, they must be in line with God’s Word. (So for example, if someone is poor and needs money, going around saying “I’m wealthy! I’m wealthy!” won’t get them anywhere, but confessing the Word that says God desires they prosper, and that He supplies all their needs I 
do believe will reap results. I believe this applies to any aspect of need in a Christian life, but I know many disagree with me there. [PM me if you want more details, because this tangent could go on forever].)
I liked and understood where you were coming from with the verse that says “an undeserving curse will not alight”, and I agree with it. Typically, I don’t fear words that wish evil upon me, because if it is an undeserving curse, the protection of God will keep me from it. If someone came up to me and wished me ill, in my case, I wouldn’t be afraid because I recognize its evil and know it cannot affect me. However I do believe our words hold a physical power if we continue to use and abuse the gift of speech towards our fellow man. In saying so, I quote this verse:
NKJV wrote:
 A man shall eat well by the fruit of his mouth, 
But the soul of the unfaithful feeds on violence.
He who guards his mouth preserves his life,
But he who opens wide his lips shall have destruction. – Prov. 13:2-3
If we break this down, see what can be understood from it: “A man shall 
eat well by the fruit of his mouth.” This assumes very strongly that something physical is gained by what you say, and by choosing the right words, you eat well of it. In guarding your mouth, you preserve your life. Not just by guarding your mouth from saying something that would offend another and put your life in jeopardy due to their wrath, but protects your life from the effects of careless words you might inflict upon yourself.
Bible wrote:
Do you see a man hasty in his words?
There is more hope for a fool than for him. – Prov. 29:20 (NKJV)
Reckless words pierce like a sword,
But the tongue of the wise brings healing. – Prov. 12:18 (NIV)
Reckless and hasty words bring bad things to life. The same power that they have when they escape your lips, and you see the horror of them on the face of someone you have offended; the same way you cannot possibly ever retract something spoken; this is something I often think Satan takes advantage of. 
A family mourning their son’s death in a car accident might bewail, “Why did this happen?” And yet not think of the times they may have said “You’ll kill yourself if you keep driving that way.” I know of many personal experiences where the words we have spoken have come back to bite us just the way we said they would in the beginning.
There are so many Bible references that state how important keeping our tongue on a leash is. I will quote a few here:
NKJV wrote:
In the multitude of words sin is not lacking,
But he who restrains his lips is wise. – Prov. 10:19
The mouth of the righteous brings forth wisdom,
But the perverse tongue will be cut out. – Prov. 10:31
The tongue of the wise uses knowledge rightly,
But the mouth of fools pours forth foolishness. - Prov. 15:2
There are many warnings in the Bible to guard our tongue, and to watch our words. You could read them in such a way that it applies both to spiritual/ emotional death, and also physical death if you so choose. However way you read it, the most important point of all is that God places high value on the things that we say. He doesn’t want us to spend our words recklessly or hastily, or in a manner that we believe “doesn’t matter”. The things we 
should be speaking are indicated by verses such as:
NKJV wrote:
The mouth of the righteous speaks wisdom,
And his tongue talks of justice. – Psalm 37:30
Let no corrupt word proceed out of your mouth, but what is good for necessary edification, that it may impart grace to the hearers. – Eph. 4:29
But let your ‘Yes’ be ‘Yes’, and your ‘No’ be ‘No’. For whatever is more than these is from the evil one. – Matt. 5:37
I’ll be first to say I fail at these instructions daily, hourly, and ofttimes even minutely. 

 But by God’s grace, I hope to someday be able to speak in any situation and have what comes out of my mouth be Godly and edifying. (I could overflow into the subject of sarcasm here, but I’ve no idea where I stand on that matter, only that often it can be taken too far. I’m the last to speak about it anyway, because y’all know how radiant an example I am of snarky sarcasm. 

)
So in conclusion: do our words have the power to kill spiritually and emotionally? Yes, I believe so. Do they also have the power to kill us physically? I believe so, though I don’t believe it always happens. Satan is always looking for an opportunity to smite us and I believe our subconscious can often be a tool in his hand. The latter may or may not be true. But based on what I know, and what the Bible says about the words we speak, is it worth the risk? 
Personally, I don’t think so. Hencewise:  I endeavour never to say anything negative, but speak positive words of Scripture to the best of my ability. 

 Those are my lengthy, scattered thoughts on the subject. 

 Please ask me questions! I may have missed clarification somewhere… 
