When you retire at lvl 31 or higher you can increase the stats of an item, giving i more defence, dmg, speed etc.
For example, i heirloomed my flamberge 3 times to masterwork (3 times is the max currently)
A loom point is the point u use to heirloom.
Some players sell these points by taking an item from another player, heirlooming it, and giving it back for a price.