"FileMaker Icons (icl8 + icl4)" is a ResEdit file containing color icons for FileMaker Pro. They aren't too fancy so that they would be distracting, but they are what I think Claris would have wanted to have if they weren't still using black-and-white icons.
To paste the icons in "FileMaker Icons (icl8 + icl4)" into FileMaker Pro, simply open ResEdit 2.1.1 or later and open "FileMaker Icons (icl8 + icl4)" and the FileMaker Application from within ResEdit. Select everything in "FileMaker Icons (icl8 + icl4)", copy, and paste them into the FileMaker Application's window. (It is easy to tell which one this is because there is a lot of things in it.) Then save and quit. In order to make the icons appear, you may have to restart and/or rebuild the desktop file. To rebuild the desktop, restart and hold down the command and option keys.
I have also included a folder with a color FileMaker Application icon on it. I have found that it is safer to copy-and-paste this directly onto the Application like you would any other icon onto a folder than to insert it using ResEdit. An icon for the FileMaker Application is not included in the "FileMaker Icons (icl8 + icl4)" file.
Although I am 99% sure these procedures are totally harmless, I am not responsible for any problems that occur, so keep a copy on another disk! If problems do occur, throw the damaged file away and EMPTY THE TRASH!!! Restart the computer and copy the backup back onto your hard disk.