First off, the Vinland Saga anime is a nice mixture of historical fiction and creative liberties in my opinion, although I would have loved for a little bit more accuracy in drawing weapons and costumes.

The anime is set around 1014, when king Sweyn Forkbeard attempted to conquer Eastern England and, after his death in that same year, his son Knut "the Great" would go on an be the ruler of what some historians have dubbed "North Sea Empire" or "Anglo-Scandinavian Empire", since it included Denmark, England and allegedly even Norway.

The axe heads being carried on a pole make me believe to have been heads for two-handed axes, sometimes referred to in historiography as "Dane axes". The Bayeux tapestry narrates the events of the Battle of Hastings of 1066, roughly two generations later, but it shows the presence of what said axe may have looked like as carried by Anglo-Saxon warriors. Such weapons, being rather big, perhaps in the region of 1.5 to 1.8 meters tall (something around 5 to 6 feet) I believe were carried much like spears would in normal conditions, by hand or perhaps hanging on your shoulder while marching with your arm resting on the handle acting as a counterbalance, or maybe you could use it like a walking stick and actually lean on it while walking.

However, what is depicted in the image is not a common situation, for two reasons I believe. Number one is that, if I recall correctly, throughout the anime that type of axe is used both as one-handed and two-handed. In the case of the former we must assume it's the author's creative liberty, but a few archaeological findings from the early XI century (so in line with the show's time period) hint towards bigger one-handed axe heads, like these from Dublin Museum and dating back to 1014's Battle of Clontarf between the semi-mythical Irish king Brian Boru and Hiberno-Norse Sigtrygg Silkbeard, king of Dublin.

However, I suppose that it could be possible to carry great quantities of axe heads if placing them inside sacks or bags wasn't a feasible thing to do. The tapestry shows a group of men carrying iron mail armours hanging from a pole and carried on the shoulders, which can hint us in the general direction of such practices taking place for a variety of reasons. Smaller axes might be carried around much like modern historical reenactors hypothesize: by sliding the shaft inside a leather loop or metal ring and letting the axe head lock itself in place but still being capable of drawing it easily and without hurting yourself. This, I believe, is not a completely unrealistic way to carry an axe.

As for the sharpened poles, I think they might have been used for camp fortification, either vertically arranged as to form a palisade around tents and supplies, but also to be placed into the ground diagonally with the sharp end facing a potential enemy charge.

I hope this answer helps your inquiry.