Whether there is a physical component to Uriel's manifestations or not, I still don't think he has blood. Now, the blood his mortal form had would likely have had some interesting properties, but it would still have been just human blood.
And BTW, I would not classify MacFinn as anywhere near Uriel in power. That higher circle wouldn't have done diddly to a being who can snuff out galaxies with a though.
That's power level, not genetic make up, like comparing WL with MW. Both technically fairy..
Putting Macfinn's beast on a different weight class that hasn't otherwise been used was intentional. Though the only quantifiable difference I can point out offhand is, Being both the spirit of rage and the human MacFinn simultaneously gave one of the biggest superbeasts the ability to directly effect fate, unlike creatures for whom higher circles hold no purpose. Angels can do similar, it just costs them so much more on the scale of things, i.e. personal balance. Archangels though, (maybe i'm pointing the idea of Archangel too close to the idea of 'horseman' for reality...) seem to have the quantity of both mortal and immortal one the same being.(as opposed to being a mortal combined with an immortal mantle)
Random incomplete tangent:
Woj is, N can't effect Angels because they are too absolute. Take the example of Lash possibly being the Reaper in GS, she came to being by dying utterly, combination of soul and spirit fused to new form, ala anybody dying per Bob. An Yes, it's very indicative she was a spiritual entity existing in a human that became an Angel proper.
So.. Take say TWC, who died utterly(especially if they used Medea's Bodkin on him as the spear tip) but was also reborn utterly. He is both powerful diety and Mortal underneath, but they are one and the same thing. Giving him Archangel like power and Mortalish form(like Mac perhaps?
) and a heavy need to make no choices or take no actions because of unintentional results.