My advice: stamina potions, strafing around it in circles, and a lot of shieldbashes. Frostbite spiders are uberhard to ddodge for me until I get that slow down time block perk.I finally decided to up the difficulty, and started a new character on Adept.
The stupid spider in Bleak Falls Barrow took ages to kill. I shot one arrow, ran away, waited for the sneak eye to close, and went back to do it all over again, and again...
Now I want to experience starting a game in legendary difficulty.
I know, this is what has me seriously considering deleting my main character--a character I've spent 130 hours on--and restarting all over again. I'm hoping even wolves will be dangerous.