: A Shade, one on one (in game) with an Avatara will almost
: certainly lose. So they must have lost SOMETHING when
: they became Shades.
According to GURPS, their undead bodies can't naturally regenerate mana in the same way that a living mage's can, so they /need/ energon cubes for spellcasting (even for spells of lesser power- living avatara need energon cubes for dispersal dreams simply because their bodies can't naturally handle the vast amounts of raw power needed for the spell.)
As to why Avatara will almost always beat Shades 1 on 1, this is probably due to a combination of two factors:
1) Alric, the only Avatara who we ever see in a duel with a Shade, might be a cut above the "average" Avatara.
2) Due to being dead, a Shade's muscles and sinews will have dried and stiffened, putting a severe limit on their agility- the theoretical knowledge of swordplay is all still there, though.
