It appears that this was a weird and tragic mistake according to an update. Real grenades were put in with a bottle of whiskey as a joke. Since it was a new type of grenade, he didn't realize they were real.
Update:
More information from law enforcement officers on the tragedy with Chastyakov.
The details of the death of Zaluzhny's assistant Gennady Chastyakov, who died from a hand grenade as a result of an accident, have emerged.
According to law enforcement sources, the grenades were part of a "gift set" presented to him on his birthday by his colleague, Colonel Timchenko. He has already testified that he himself decided to make such a gift, placing a bottle of "Black Label" whiskey and 6 pomegranates in a wooden box.
This was confirmed by three witnesses during which the colonel handed over the gift. He even said to Chastyakov: "It's hard to surprise you - that's why I'm giving you combat grenades and a bottle of good whiskey."
Obviously, Chastyakov took it as a joke. Because later he took the children from school and began to sort out gifts with them. He thought that in the box were not combat grenades, but glasses of a specific shape.
By the way, Timchenko kept two grenades for himself. The photo shows how they look. Journalist Andrii Tsaplienko.
As they say, "regulations are written in blood".