Yes when you separate them enough they are two objects with no separation. That's irrelevant to whether or not when the two pieces of the dagger are close enough they are two pieces of the same object WITH a gap or separation. Nor is it relevant to the spell whether or not someone places those pieces close together. Manipulation is not forbidden by the spell, nor does it even make sense to forbid it.
The spell by intent and by language allows for Mending to repair objects that are completely broken, providing those objects and/or breaks are small. You are conflating complete with large, rather than looking at the size alone. The break is complete once that crack widens enough to become a separation, but it isn't large for the purposes and intent of the spell.
How are you not doing the exact same thing in ignoring the definitions that refute you? There are in fact definitions that do apply to objects as I posted.
There can be a gap between two pieces of an object. A single object when broken in two has a discontinuation/discontinuity. There is an interval between the two pieces. I hadn't known what lacuna meant, but it fits as well. those qualify as a disruption to the uniformity or continuity of the object.
Then going to synonyms for gap or opening. A broken object can have space between the break that is total. The same for a gap. And you can split something in two. I mean, the last one is a classic example of a synonym that is often used for objects. "I split a log in two with my axe to make firewood."
Man, if it's a definition then it CAN apply to Mending. You just argued that if there are more definitions that don't apply objects, then none of the definitions that do apply to objects can ever apply to an object. Language doesn't work that way. All definitions are valid and on the table to be used.
I'm not the one cherry picking here. You are. You are deliberately excluding valid definitions for both break as a noun and it's synonyms that can(you'll see I say can, not do when I talk about this) apply to objects and therefore Mending.
Nothing in the wording of Mending excludes any of those definitions, but it does confine itself to objects, so definitions of break that don't apply to objects are out, and ones that do are in. That means that the ones you are cherry picking and mean cracks are in AND the ones that you are deliberately excluding that mean a complete break of the object are also in. I am including all of them which is the opposite of cherry picking.
Again, English doesn't work that way. You don't get to unilaterally declare for the world that the definitions of break that apply to objects having complete separation are no longer valid just because there more definitions that don't involve total separation.
Are you telling me that you haven't in your life ever heard people describe an object that is in pieces as "broken?" I have, and by an uncountable number of people. When I dropped a plastic cup a few weeks ago a piece of it broke off, I told my wife that I broke a cup. I didn't tell that I had cleanly broken a cup, because that would have been silly. Using the word "clean" when talking about breaks only applies to certain types of things and only at certain times. A bone would be one of those times and is not even used to describe all complete breaks of a bone. It is used to describe a complete break of a bone that causes no malalignment.
The bolded sentence is incorrect. Nobody is telling you that break doesn't mean a crack or fracture in an object. We are just not cherry picking only those definitions and excluding the ones that include complete breaks.
Nothing in the spell says a small amount of damage. Literally nothing. Only that the measurable size of the break be small, which a complete break of a slender dagger is. You keep talking about language used, but ignore the deliberately used language of "slender." There's a reason why they say slender dagger and not dagger. It's because a small break size is purely measurable in length/depth and has nothing to do with whether it is partial or complete. There is a reason that the objects described in their language are all very small.
You have also brought up Make Whole as evidence that Mending doesn't fix complete breaks. That is not logically sound. Yes it's a level 2 spell which makes it more powerful, but it describes in what way it is more powerful than mending. Mending only affects an object that weighs 1 pound or less(again, must be small) and only fixes a single break(partial or complete). Make Whole on the other hand affects an object that is up to 10 cubic feet per level of the spellcaster, so a 10th level caster could affect a single object that is 100 cubic feet in size and has no limit to the weight at all. Further it fixes multiple breaks in that object. So while I could mend a broken statuette with a single break with the Mending spell, with Make Whole I could repair a completely shattered Michelangelo's David if I were 20th level.
Destroyed and ruined in D&D terms simply mean unusable for it's function. That's it. It doesn't mean annihilated. It doesn't mean shattered into 100 pieces. Those words just mean unusable for it's purpose, which a slender dagger broken into two pieces is.
These are the guys who made the spell. And it literally says that the only difference is the materials it can be used on(i.e. no metal). You keep arguing that words mean things and here you are ignoring the meanings of the words used.
"Mending will only work on pottery and glass;
otherwise it is identical to the magic-user spell. A piece broken into a number of pieces (not fragmented to shards or dust) can be put back together."
The logical conclusion is that the magic user spell allows pieces to be welded back together.
And I agree with that in principal. Except for the part where we would need to homebrew it working on the dagger
I have used house rules for every edition of the game except 4th since I did not play that edition. So long as the group is having fun, nothing else really matters, including not allowing Mending to work on complete breaks.
1. Broken means damaged and no longer working. It can mend
broken objects PROVIDED it has but one
break. Broken
can mean into pieces, it can also mean damaged, such as a crack, and no longer working. It doesn't mean it IS absolutely broken into pieces. That broken must adherer to the condition in the conditional part of the sentence.
Broken is the only word used in the spell description which can mean separated into pieces, but the authors stipulated that the type of broken must match that which is "a break", and.....
2. "A break" does NOT mean total separation. The only instance that is does is with an
idiom, clean break, which has its own meaning independent of its individual words. It means "a total separation", it does not mean "a large break". Sorry mate, but you're wrong.
"Mending only affects an object that weighs 1 pound or less(again, must be small) and only fixes a single break(
partial or complete)."
Your words, not the author's,
your perception of what "a break" means. You think that it could mean "a space" could be some artificial gap, even though it contradicts the vast majority of every other synonyms. We could go through each one and draw it, go out in the real world and see what each object looks like, and see if this "space" as you define it lines up with the rest.
3. The cumulation of all the definitions of the synonyms used for objects is overwhelmingly still attached to the source and coincide with the wording of the authors and applying the rules. It doesn't contradict anything until people define it as to mean a separation. Cherry picking is choosing the 1 percent out of the 99%, it is not choosing the category to which the object in question belongs!
4. Context is absolutely important when defining words, that's why the noun has a different meaning inferred for objects than it does with "a page break", you don't need to fish around in other contexts to find a relevant meaning for one that is
already defined. I'm actually including every thing in that category as a means to prove that the root word in fact does not mean a total separation. A crack is similar to a fissure or a crevice, while those subtle differences change the meaning of the word, they are all breaks and match with each other. A rush or a dash in a particular direction, ie make a break for it, has nothing to do with a small gap or hole in an object. An interruption is NOT the same as a fissure or a crack, the synonyms listed for a break.
1. interruption, interval, gap, hiatus, lapse of time, lacuna, discontinuation, discontinuance, discontinuity, suspension, disruption, cutoff (not to be confused with
cut off), stop, stoppage, cessation, caesura, surcease (jeez, there aren't many words I come across that I don't know but this lists a couple

)
2. gap, opening, space, hole, breach, chink, crack, fissure, cleft, rift, chasm, tear, split, slit, rent, rupture
You're going to tell me that these are comparable????? They're totally different and would not be used synonymously.
Look at those examples in #2. Which ones mean a total separation, and come at me again with the cherry picking argument.

What's the rational common denominator there, that there is a total separation, or that it means a partial separation? Open the window a gap is not wide open. A space in the traffic is a break in continuity, suited for the first definition and not as an object. Is it not? Which synonyms, meaning similar words to the defined words, are suitable for "traffic"? A space, which is it more similar to, a rent or rupture, or a suspension or disruption? Totally different context. An opening, a cleft/tear or a hiatus/interval? Put the words beside every word that they're comparable to and it's EASY to see what it means, although it may not agree with how you have come to understand it. Relevance is not cherry picking nor is it omission by obstinance, my friend. It's knowing the language, and I'll be happy to explain why one thing is relevant and the other is not. These posts are quite lengthy, we both try to keep it as terse as possible by not overexplaining ourselves.
5. Viewing "a break" as a percentage is
science, and more precise than a human
perspective. I'm being accurate, precise, irrespective of what I think is small or large. What you think is large or small doesn't change the fact of what is large or small, relative to the size of the object in question. The larger the object, the smaller that 1 inch is. The smaller the object, the larger that 1 inch is. That's just common sense!
This is the fundamental difference of beliefs, I think, that is the core of the argument. I believe the accuracy of language and science determines the relative size of a break, where others believe that the size of the break is determined by a human perspective. What do you think? In that regard, neither of us are wrong from our relative perspectives. I can't disagree, that an inch isn't large. A 1 inch crack on my windshield is small, but a 1 inch crack on the glass of my watch covers the entire face, and would be hideous. To me, relativity matters, as much as word choice matters.
Pierce your ear and put a 1 inch hole earring in it. It's HUGE! But in a storm giant, it's just a normal piercing. Relative! Am I wrong there?
I could see why you think they way you do, but I'm only ignoring the definitions not relevant to subject matter, because it can be easily taken out of context. The definition has been given and used in context and synonyms provided because that's categorically the way it is to be approached and used, and others might be related in meaning but not suitable. The definitions are parallel, but the examples are completely different ballparks.
I still say that people making certain arguments aren't accurately representing RAW.