Looking at the image, the first thing that is somewhat similar came to my mind was, Windows Registry Editor.
According to me there are 2 changes you could do, they are:
1) Keeping three columns as it is and just removing (replacing) top and below buttons of ADD,DELETE, SAVE & CANCEL.
2) Changing layout to two columns and on double click of attribute from a list, popups the form to fill rather than already utilizing space. - (Better one)
Also you could combine both.
- 1) Remove those buttons and on right click show option to add or delete new ones(Talking about the first column). Like on right-click over "mining_vehicle" show different options like a) Add new b) Rename c) Delete, etc...
It will negate necessary of the buttons like SAVE and CANCEL.
2) Also you could try just two columns left one(1st column) as it is but with modifications as mentioned above in 1st point here.
And for 2nd Column as it is but on double-click or right-click along with option of edit. Which leads to appearance of popup form which currently your 3rd column.
- "Right click options removes the Add/Delete buttons, but how the user will save/cancel a new Item?"
Similarly if user perform right-click on CDH40, user will get same options or whatever you have/want for them.
And for the Name and Value: