How to get to collectibles
First, you do /profile and click on the iron chest plate that is named "Collectibles"

After you do that it takes you to another page that has all the different types of collectibles on it.
Kill messages can be earned by participating in Loka ranked PVP. Depending on what tier you get determines the rarity of the kill message. There are a total of 94 kill messages (Subject to change).
Battle Helms
These can be earned from quests, or donating money and becoming a supporter. There are an unknown amount of battle helms that currently exist.
Titles
There are 24 different titles/suffixes that can be earned, different titles and suffixes can be earned by donating money. Some titles are also earned by winning pvp tournaments, ranking high on a Loka PVP season, fishing, and voting for the server.
Pets
There are currently 2 pets that are availible, both are acquired by becoming a supporter.
Player FX
These are effects that come off of you while at spawn, they do not work outside of spawn or your town. There are 2 that can be acquired, both by becoming a supporter of the server.