Call of Duty: Black Ops III

For this achievement you only need to upgrade ONE of the FOUR Bows.
The easiest bow to upgrade is the wolf bow.
But there is one achievement called Der Meisterbogenschuetze that you have to upgrade all bows in one game so might as well try to upgrade them all (If you are playing with other players they can upgrade the bows as you will still get the achievement).

here is a video with a step by step

amazing video walkthrough , credit goes to powerpyx for this!

This Achievement can be gotten by doing to things the first is getting the Wrath of the Ancient regular bow and the next is to upgrade that bow into one of four elemental variations. Below you will see a Wrath of the Ancients guide along with upgraded bow guides (right now just the Wolf one aka the easiest to upgrade) all other variations will be updated.

Wrath of the Ancients Guide
--------------------------------------

Storm Bow Upgrade
------------------------------------

Wolf Bow Upgrade Guide
---------------------------------------

Void Bow Upgrade Guide
-----------------------------------------------

Magma Bow Upgrade Guide
-----------------------------------------------

This achievement i for upgrading one ancient bow. However the Der Meisterbogenschuetze achievement requires you to upgrade all four bows in one game. So you will get this achievement along the way. To upgrade any of the four bow you first need to obtain the normal bow. After that you can choose any of the four. The Wolf/Green bow is the easiest and the Fire/Red is the hardest.

Normal Bow:

Wolf/Green Bow:

Skull/Void/Purple Bow:

Electric/Lightning/Blue Bow:

Fire/Red Bow: