Etherium Waraxe
A weapon worthy of true viking... or a true lumberjack. One of these guys should suffice.
It can be created in a Crafting Table, via shaped recipe:
When mining a block that waraxe is effective on, it will break additional such blocks in 3x3x3 area centered around the broken block. This effect will not trigger if player is holding Shift, however, allowing to mine individual blocks if it's required.
Etherium Waraxe has 3000 points of durability and slightly faster breaking speed, similar to other tools made of Etherium. It's noticeable difference from regular axes is that it can effectively harvest not only Wood, but also Leaves, Cactus and Bamboo.
It is also considered one of three etherium tools that are effective as weapons. Etherium Waraxe has longest attack cooldown of them all, even longer than that of vanilla axes - but deals 16 points of damage on regular attack, which is, needless to say, a lot. Combined with ability to disable shields, the waraxe can be especially deadly in PvP encounters.