This might be worth a try:
Setup a search for your terms.
You should now have a list containing both Feat and Feature songs.
Select all the songs in the resulting list.
Now, do "Get Info..." CMD-I
I'm assuming the word Feat and Feature are in the same field, so if you type in "ft", and check the box next to it, you will only update that field for all the selected songs. (it only updated/overwrites modified fields / checked fields)