Recommend a visual "objective" XML editor with the ability to export to JSON

Question

Programming

Hello!
Perhaps I'm not expressing myself exactly in the title, here's what I mean and why:
I'll start "from the stove." I am making a toy on Unity for mobile phones (iOS/Android) in C#, respectively. I do not want to use standard libraries for serialization / deserialization because of their rather large footprint (about 1.5 mb). I'm talking about System.XML.
Therefore, I decided to map the data to classes and write back to XML manually (by the way, if anyone knows the ones tested on combat applications, I also ask the studio).

From this whole situation, a couple of problems appeared:
1. The complexity of editing long XML with a list of, say, game items - there are 642 of them at the moment, they are all inherited from the same class in the game itself, but have their own characteristics.
2. The complexity of modifying the basic structure of one element.

Therefore, my question is:
Is there any editor, technology, even methodology that allows you to make some “templates” for xml blocks, so that later they can simply be filled with data, and so that, say, when adding a new field to the template, it simply adds an empty field to all elements in the common tree.

I have now installed oXygen XML Editor (http://www.oxygenxml.com/), but have not yet found such functions in it. I'm almost sure that all this is called something, I just don't know the terminology.

The result should look something like this:

/*Template ItemBase */
<item>
<id type="int"></id>
<name type="string"></name>
<description type="string"></description>
    <data type="object">
        <lvl id="1">
                <damage>50</damage>
        </lvl>
        <lvl id="2">
                <damage>60</damage>
        </lvl>
        <lvl id="3">
            <damage>70</damage>
        </lvl>
    </data>
</item>

and then in the general template to be something like this:

<items template="item">
+ добавить новый item
</items>

Answer 1

In fact, you need a game admin panel, or a visual database add-on + a file, like this . Now I have the same problem, although there are not so many objects, so it’s not too lazy to reload with my hands. It is also possible to look towards exporters from Excel to XML.

Answer 2

It seems that I found where to dig: XSD
http://en.wikipedia.org/wiki/XML_Schema_(W3C)