Safari download bar rar file icon show as VLC icon,which associate to The Unarchiver should shows its icon
If you want .rar to be opened with The Unarchiver as default, you can:


Get info on this .rar file
Set file to open with in the info window
Click Change All


The Change All button will make all .rar be opened with The Unarchiver and have The Unarchiver icon on it.