Assuming max numbers for attacker's weapon skill as a warrior, and attacker/defender agility/luck attributes both maxed at 100:
100*1.25 + 10 - defender's sanctuary + (100-100) * 0.25 + (100-100) * 0.125
which reduces to:
135 - defender's sanctuary
Note that an Orc warrior would use his berserk ability and get an additional +100 attack for 235% chance to hit for 60 seconds.
So with 135 points of sanctuary and an agility/luck equal to your opponent, you would be invulnerable to physical harm from non-orcs. This can easily be done with CE items of clothing/armor. Add on an actual spell, "100 points of Sanctuary for X seconds" and even a berserking Orc won't be able to hit you for the duration.
With 196 points of sanctuary from CE items (I also had 165 Agility and Luck) I did Hircine's Hunt in Bloodmoon and none of the werewolves could touch me. Only the five Hands of Almalexia's personal guard have been able to hit me so far.