I assumed you’re just stabbing the enemy with the ‘spike’ (the end used to plant the banner in the ground). Practical? eh.. maybe not, but just how it goes. I’m sure the intention is to have some trade-offs since the banner has the resolve buffing capability, however in my opinion I don’t think it really needs to have the tradeoffs. The weapon has to be held to receive the buff, and as a weapon it is mediocre in the mid to late game.
From a combat perspective it is outclassed by the pike simply by the pike having an alternative attack (push), and the longaxe and billhook (imo) are both better than the pike.