I just defeated Mercurio and I obtained these two items that don't have an item description, one is a Femur that i can use as a weapon but doesn't have any stats. The other item is a Holy Cross and has "unidentified" in its description. Can someone explain why.

Are you asking why you have them or why they are unidentified? If the latter, you have to use the Spirit Touch discipline (or a scroll) to identify them.

Thanks for the answer, for the Spirit Touch discipline can I purchase a scroll from a shop or do i have to obtain it from loot?

You can buy the scrolls from vendors. I'm early in the game, but the Gypsy in Golden Lane sells it. It also becomes an available Discipline for your vampires under the Auspex category.