Snipers generally mean people who attack in a way that will ignore a player's current armour or prayers. So now a sniper would generally have something like:
For mage; Runecrafting robes, normal/gravite staff, fire blast runes.
For range; Green dhide (coif optional) power ammy, green vambs, and longbow sighted, chaotic short, or a normal maple bow.
For melee; Rune gloves, beserker shield, rune scimitar, and gravite 2h