In my own rulesets, I use the WOTR courage system, but passing on 12, and I find it makes them only a little bit more important. A better solution (IMO) would be to make a courage value that you must pass with one D6 (ie you have C4, so when you make a courage test you need to throw 4,5,6). However, that would require assigning everyone a new courage value. For an "instant" solution, this would indeed help elves, but make Ringwraiths even more overpowered as well. In general, I find Terror is not too weak. And as you pointed out, certain spells would make problems as well.
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"... Telchar wrought it in the deeps of time."
-On Andùril, The Lord of the Rings