(urth) Wolfe's brilliance or my denseness?

[Lee Berman]

>Jeff Wilson: There has to be some sort of connection to account for the brilliant 
>blue glow. It might be just the relic of blood on the thorn that was 
>encased in the gem, but that doesn't explain the lack of glow coming 
>from any other of Severian's shed blood when he uses his restoring gift.
 
 
IIRC, the thorn is drenched in Severian's blood soon after he eats the brain of the old
Autarch, becoming the New Sun (within the confines of the story of the first 4 books).
 
I suppose any blood he shed previous to that (at Baldanders Castle, at Orithya, etc.)
was just the blood of the guy, Severian, and has no power. Thus, Severian's powers actually
do come from the jewel for most of the story.
 
I give Wolfe a bit of literary license for UotNS. Faced with the choice of Severian shedding 
no blood in that story or having every violent episode creating "Claws" out of Sidero's fist,
fusil butts and pavement stones, I guess Wolfe decided to skim over that difficulty and reserve 
the claw puncture as a one-time mystical event.
 
I'd say the ploughman's explanation for the color is that the claw is encased withing a 
sapphire jewel.  Once it is freed of that encasement, the claw's light is white. The choice of blue 
is a nod to the doppler blue shift appearance of the White Fountain as it hurtles toward Urth. Blue 
may also lend itself to the phenomenon for which Severian feels the light from the jewel is cold, 
as it represents energy leaving him, while it is a warm light to those receiving the energy.