The orcs saw the maginificient display of skill from the little fight Kevin had with one of them. They saw how easy he had defeated one of the strongest orc they have. From that act only, they knew they stood no chance against him.
So they bowed in defeat as per tradition of all orcs. In that way, the one with the upper hand will cease fighting and instead request something from them.
Technically, they were bowing in defeat to Kevin, and was just preparing to ask Kevin for a request. That was when three individuals appeared right beside Kevin.
They thought Kevin must have summoned them to fight against them, and even though they would eventually be defeated, they chose to fight to death.
Each one of the orcs drew out their weapons. Some carrying large axe, some swords, others spear. They were large and heavy than a normal elf's weight, and with just one swing of the weapon, a great amount of energy will be let out of it.
