You now need to use the "Minor Necromancer Orb" in battle against other players (PvP) to get the " Faith of the Vigilant Guard" collection pieces. Once you get all the pieces and assemble them you will be able to purchase the next level Skellies which you can use to get to 3000 reputation. As you are level 27 you can skip the level 23 Skellies and purchase the level 27s. And work your way up to 3000 reputation. If you uncheck the little available box in the store you will see the other skellies available. Hover over each to see what you need to level each time. Or click the reputation button and then the Vigilant guard reputation tab. Then scroll down to see the Skellies for each level of reputation and hover to see what you need to level. You can buy the "Minor Necromancer Orb" in the shop under the orbs tab. You will not get a collection piece with each orb, so be patient. The orbs will not harm your opponent in battle. So keep using till you finish the collection.

If you dont use the level 23/27 skeles you will no longer advance your reputation, any level 16 or 20 skeles do not increase your rep beyond 1000, 23 and 27 do not increase beyond 3000, the next not beyond 7000 etc

Almost every fianite mentions in it's description max reputation you can develop with them. Also aso already mentioned by BIGBEEF and greatsword - you will need access to level 23/27 skeletars to be able to develop your Vigilant Guard reputation any further.