Seeing as the family dromeosaurie is extinct, there is no way to know for sure, but as a paleontologist and an adventurer, I'd go for its neck, or somewhere in its chest area to try to puncture a vital organ.
he has a weak spot for red heads
After bathing in the River Styx his "Achilles Heel" or weak spot was his underarm.
terds
his weak spot
Achilles' heel was his weak spot thus the saying that someone's weakness is their "Achilles heel."
In the crust the weak spot we have is the Magma Chamber. But, deep down to the mantle such weak zone is the Asthenosphere.
The weak spot of an alligator is it's somach
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His heel
his pride
Stomach
An "Achilles heel" is a person with a weak spot.