1)Medallion of the horde (Non-epic)
2)Merciless Gladiator's Mail Leggins + Runic Spellthread
3)Merciless Gladiator's Mail Armor + 15 Resiliance + Socket for meta gem
4)Merciless Gladiator's Mail Spaulders + Scryr/Aldor enchant + Socket for meta gem
5)Merciless Gladiator's Mail Helm + meta gem + other socket
6)Merciless Gladiator's Mail Gauntlets +20 spell damage

Do those 5 in that order. socket with rare/uncommon quality gems, dont use epic gems until you get season 4.
Meta Gem: +12 Spell Crit, & +3% increated crit damage, requires at least 2 blue gems.
Socket other gems priority: Spell Damage, Spell Crit, Resilience, Stamina.

7)Merciless Gladiator's Spellblade? + 40 spell damage
8)Merciless Gladiator's Barrier + 12 Resilience


9)Guardian's Mail Girdle (Season 4 belt but doesn't require arena rating)
10)Guardian's Mail Bracers (Season 4, 1575 rating requirement)
11)2 choices here, Guardian's Mail Sabatons (Season 4 feet, 1700 rating requirement, and if you dont have 1700 rating...)
11.5)Vindicator's Band of Dominance (Season 3 ring)
12)Guardian's Band of Dominance (Season 4 ring, 1650 rating)
13)Guardian's Pendant of Dominance (Season 4 neck)
14)Medallion of the Horde (Epic 40k honor trinket)

By now you should have some arena points and should be able to get Season 4 gear, just upgrade your season 2 to season 4 as you get points.

15)Sergeant's Heavy Cape
16)Battlemasters Audacity (trinket)
17)Totem of your choice


EDIT: Whoops, I clearly forgot to read the part about you doing 5x shaman >.<

but yes, weapon as 7th, the weapon you get from leveling to 70 is close to what S2 weapon is, so getting 5/5 S2 armor is better to get before weapon.