Only buffs level 49 and under can be placed on toons under level 42 I think, level 43 is like up to 52, level 44 is up to like 57, and level 45 is up to 60, (I know 42 can get Clarity II and 45 can get KEI, but also I remember 46 can get Aegolism, but not Virtue, so it's weird, I think Spirit of Eagle is 54, so you would probably have to be about 43-44 to get it. If you try to stack a spell onto a toon that is not the appropriate level or class that can receive it, it boots you to character select. It booted me a while back when I tried to give my rogue (54 at the time) Spirit of Cheetah, but it worked when I gave it to my druid.