Oooooh, that's a sickener .
Now't I can see. It loos like the whole limb went bang, so I think that shows it was evenly stressed, just something made it go bang.
I've learnt that sometimes this stuff happens and you can't always say why... we like to have a reason, maybe the wood was too dry, maybe too much reflex, maybe overdrawn, maybe a bang on the back or a patch of weak grain (wind shake) or a manky knot.
Just have to move on.
I hope it hasn't left you in a awkward situation, (mind a little embarrassment is good for the soul).
I feel your pain 'cos that was a gorgeous bow

.
Attached is my guess as to where the failure started.
Is there a prize for the closest?

Del
BTW. Did you shoot it in? I like to get at least 50 arrows through a bow, ideally 100. Can't with warbows tho' as I can't draw 'em these days

.