Air 9 bless: useless?

[Sandman]

Maybe I'm missing something, but 75% shock resistance seems awfully weak compared to flaming weapons, quickness, regeneration or even twist fate. I suppose it might be useful if you're making heavy use of lightning spells, but even then, you're still going to hurt your own units a bit, and it's obviously limited by the research needed, whereas the other level 9 bless effects are useful immediately.
Additionally, there's no really cheap option for getting air 9 either, like the oracle or statue for astral 9.
To cap it all, there aren't even any spells which require air 9; the highest requirement for an air spell is 7 for fata morgana.

The standard air shield effect is decent enough, but it's hardly strong enough to justify such a weak level 9 blessing, is it?

How could the air 9 blessing be improved? There are lots of potential options; a precision bonus, storm immunity, mirror image etc. Mistform or flight would be a bit much, I think.

Personally, I'd go for total immunity to lightning and a free cast of charge body. This is not dreadfully overpowered, but it's useful from the start, and it's different from the other bless effects. Mirror image would be too similar to twist fate, and the Van and Tuatha have glamour already.