I'd been mulling over this idea in my head for the past few days of a runic gauntlet that specifically uses blood runes which for those not familiar with the concept is like a normal rune carving except with blood painted into the relief of the rune that is believed to add power to it, in this case it's a crystalline blood jewel made through whatever alchemical method you want to imagine.
The ring gears over the arm rotate either by hand (if needed) or automatically through the magical skill of the user, the image in my head has like this weak blue/white glow being emitted from the mechanism and as the runes line up for the desired spell they also then glow but in red like the blood jewel optionally with sparks if the rings are really spinnin'.

The runes on the rings of the arm are just repeats of the Elder Futhark used between the 2nd and 8th century which has 24 (not counting alternates) runes in it's alphabet, the ring on the finger has "Blood Thirst" carved into it as it either stands for the giving of the wearers blood (or victims) to the device or that it actually does that itself when needed.
The jewel inlay ring has "Transference of life essence" carved into as it takes the power of the blood catalyst and syncs with the arm wrings for spells casting.
Leather and bronze were what I had in mind for it, who knows if that'll change.

I plan on using this someday for a character so you know, don't steal it.
Possibly for Rennis if I were to rework it to be one of his armoured gauntlets like so https://www.dropbox.com/s/9kc2a5eh8yodjvs/RennisRunicGauntletRef.png?dl=0 just a mock up quickly using SAI and an old commission of him with his armour on.