Both tier 4 and tier 5 armor is epic. Tokens are used as currency for both of those tiers as well. Also, tokens for tier 4 drop in various high-end instances such as Karazhan, Gruul's Lair, Serpentshrine Lair, etc. Tokens for tier 4 are labeled as "Fallen". Tokens for tier 5 pieces also drop in thses high-end instances and from 25 man raids. Tier 5 tokens are labeled as "Vanquished".

Ex.

Tier 4 Warlock Leggings come from Leggings of the Fallen Hero.

Tier 5 Warlock Leggings come from Leggings of the Vanquished Hero.