Cut if off at the break and leave it at that. The crooked branches around the snapped off one probably indicate where the entire shrub was cut off short previously either at the production facility or perhaps the retail outlet and was able to grow back.

The reason this would happen is there is an unfortunate tendency in the industry to cut back overgrown shrubs that need to be potted on instead of potting them on. So the condition of the roots of your new specimen may be much more of an area needing attention than the one broken branch. If it were mine I would dig it up early next spring, well before it leafs out and correct the root deformities that are almost certain to be present.

Unless there was a tight knot or fist of roots I couldn't address without killing the shrub. In which case I might just throw it away.

Pretty much every woody plant I see offered here that has ever been in a container has more or less terrible roots.

if you google REJUVENATION PRUNING OF FLOWERING SHRUBS ... and very superficially study the concept ..

you will see this means nothing ...

prune it out .. and forget about it ..

if the plant dies.. its from the transplant or improper watering ... not this ...

all that said.. you have to try hard to kill these things ...

if the roots were wrapping around and around in the pot ... did you break up the roots at all ????

ken

here review the link.. lets discuss any problems you might read ..

but forget about these branches...

ken

https://sites.google.com/site/tnarboretum/Home/planting-a-tree-or-shrub

Once you have cut off the broken branch you could divide it into sections and grow yourself some more Weigela from the cuttings. Google how to if you fancy a go at propagating it.

Ken,

That link appears to be bad, gave it a few days in the event it was a temp outage. Can you try again please sir? Thanks!