Nostalrius Begins - Quality wow vanilla realm (1.12)

Hello, good people!
Im a new player to this server, thats why i might not know smth but ...
Recently, while leveling an undead rogue, ive noticed that my Eviscerate rank 3 shows up as Rank 2 in skills tab. im confused.
http://res.cloudinary.com/dtdcrhkuz/image/upload/v1432900053/Crapy_Eviscerate_r77ktn.jpg

Please explain is it a bug or a feature.
P.S I always wanted to be special but not a crippled assassin one of a kind (sadface)