Multi-Gem Shardblade

[Turin Turambar]

Would it be possible for multiple gems to be put on a shardblade, then have multiple people bond the same shardblade?

[Quantus]

I doubt it, the gem is facilitating the Connection, but among other things it seems to be tricking the deadeye spren into thinking they are still bonded, and the original bond was very individual.  On a practical side, you'd have the issues with whose Heartbeats would summon it, who could Will it to remain manifested, and eventually whose Bond would be the primary and could override the commands of the other when they issued conflicting Orders. The fact that Blades get loaned out from their Family owners (or the Kings Blade tradition) would lead me to believe it would have been tried, as the original owns would be highly motivated to find a way to forcibly take it back if the need arose.  The closest I think you could get is to Destroy the Gem of a Bonded blade so that it would loose the ability to be summoned or dismissed entirely, and then share it from there in a purely physical way. 

[Weltall]

We have Word of Peter that the bond is between the Deadeye and the bearer and the gemstone is just a go-between. If you remove the gem the bearer can't dismiss or summon the Blade but putting any gemstone onto it will reestablish the connection Yuu can't steal a blade, replace the gemstone and make it work that way so there's no reason to think that trying to put multiple gems on the same Blade would do any better.

[Turin Turambar]

the whole idea is that there is a gap in the spiritual web, and the spren fills it, I think. so from the sprens perspective, if you can trick it into forgetting the first bond, then you could (theoretically) could do so. And yeah, I thought about the summoning problem. that's what prompted the question.