Jeremy and the New Skills
As its name suggested, the first skill, [Heightened Senses], was a passive skill that helped increase the owner's awareness of the surroundings. It was such a great passive skill for the close combat classes but very hard to acquire naturally or by practice.
Moreover, the skill could evolve two more times into the [Battle Senses] and [Sixth Sense], respectively.
However, to upgrade the skill, Jeremy needed more than just efforts, but that shouldn't be too hard for the former sage as he would be able to find a way eventually.
The second skill, [Stealth], was a basic active skill of those sneaky classes who played with silence and darkness. When activated, the user's presence would reduce according to the level of skill mastery.
Its downside was that it was imbued with a darkness element; the higher the skill level, the more the darkness element being imbued.
As for why it was a downside...