What IS a focus really?
It is an item through which you focus magical energies. They were called this in GW1, they are called this in GW2. It makes a lot of sense, if we were to have it linguistically correct then you would call the items a focuser, but that sounds ridiculous, so you call it a focus. Focus: " an act of concentrating interest or activity on something", what are you focusing, magic – A focus.
It can be any handheld item: A bracelet, a dagger, a mug, a cell phone, etc.
Magical focus – a sorcery device used to focus your magical powers. Due to how wide that definition is, the device can come in multitude of shapes and sizes, so it is hard to imagine an “iconic” focus. Especially, since that iconic role is usually fulfilled by staves and scepters (or gw1 wands), which got separated in distinct groups here.
Remember, remember, 15th of November
In more tribal terms, it’d be called a “fetish”. A ritual object.
Though I don’t recommend googling that one, either.
When you research a new focus via artificer crafting, the icon given is very similar to a voodoo doll.