sym.imp.kernel32.dll_GetModuleHandleA is a flag radare2 defined for this address.
This flag name is combined from 4 parts:
sym for Symbols
imp for Imports
kernel32.dll is the name of the library
GetModuleHandleA is the name of the imported function in the library
To handle flags with radare2 you should use the
f command and its subcommands. Use
f? to list all of them.
For your case, the right way to get the flag name for a given address is to use the
fd command like this:
[0x004073d4]> fd 0x408084
You can split it to the function and the DLL name by using simple string manipulation with the programming language you are using to script radare.
On a personal note I will say that the best way to script with radare2 is to use r2pipe which is a very simple interface to radare2. You may already started using it but just in case, here's how simple it looks like with Python:
r2 = r2pipe.open("/bin/ls")
print(r2.cmdj("aflj")) # evaluates JSONs and returns an object
I suggest you to read the Radare2 Book to learn more about radare2 and how to use it.