You raise some good points!
In the classic gauntlet arcade, I think throwing the axes are a free thing to do, the only cost being your hand and how fast you can spam them. However, I do need to add a cooldown for it.
I was going to make a type of enemy that left behind a red line, however I ran out of time. Something to work on for an update :D
The blue potions kill all enemies on screen when touched, although it is not clear.
Thank you for your feedback <3