Throughout the time that Ryden spends in this world, he already loses count of how many times he is in danger both in human and monsters' hands
Despite his greatest strength be direct combat and although his sneaking and assassinating skills were not as strong, it still was not that bad
The things that makes assassination hard is infiltration and killing the target at the fastest speed without causing a commotion
Others don't have the ability to kill their target but Ryden is different
His killing power unparalled, there is almost no one in the world that can defend themselves against his sword in a one on one battle
That is one thing that made his assassination skills not bad
As for the infiltration part, in this case, that is trickier
As a Prince, Navca naturally have many guards. Many people are protecting his detestable life especially since the Empress will not risk letting his child die in the borders