If one were to identify a weakness in the 'Tentacles', it would certainly be their direct connection to Han Dong's most vital organ - the brain.
Physical damage wasn't much of a problem for Han Dong. He could autonomously close his various pain receptors, and whether it was damage from the G virus or the Yellow Sand, his body could reconstruct itself.
However, the Tentacles posed a significant problem.
Upon sustaining damage, they would inflict intense pain and harm on Han Dong… Severe enough that he would be incapacitated by the pain, unable to fight properly for a duration of time.
Ding!
The Bloodhound, formed by Tentacle Isomerization, was unable to crush the Barrier in one bite.
Instead, Han Dong was left with a throbbing pain in his tooth--a strangely satisfying sour sensation that pulled at his nerves. Hastily, he motioned for the Bloodhound to retreat back into his body.
Barely suppressing the pain, his entire arm began to tremble slightly.