this tip should be really helpful if you just started the game... i found it's pretty easy to get an aura of guarding from the "study" on the first level of the catacombs (with 3 bookshelves towards the west (one southwest and 2 northwest) and 3 barrels towards the southeast... there should also be a desk with a diary sitting on it - i THINK this is also where you can summon a skeleton by putting out the 5 candles on the pentagram and lighting them again...)... just keep reloading till you get it... i got an aura of guarding from this place 3 times with 3 seperate characters (after multiple reloads...)...
aura of guarding lvl 1 = a shield which can endure 60 points of physical damage... costs 10 mana and only dissapears if you sleep... very helpful - and will help you survive an in your face attack from the skeleton summoner if you have full hp (although you'll only have a bit of hp left after that... that thing does something like 120 points of damage per hit...)...