It's quite an obvious reason really. In the game there will be nine different weapons or blades that are available to the player, each unique in it's play style. They are:
- Pick Axe
- Glaive (En.wikipedia.org)
Each will have varying statistics, the available areas are:
- Damage - the value of damage that the blade is capable of
- Speed - the speed that the blade allows you to attack
- Weight - how much the blade will slow your movement speed
- Agility - how much the blade will reduce your dodge ability
- Resistance - the percentage of damage the blade will take when blocking
The weapons will all be equal in ability, so although the 'Cleaver'' sounds like a better choice than the 'Sword', it will not actually be any better, it might do more damage but will be much heavier. All of the blades will be available to unlock though out the game at similar times, it's down to the player to choose the ones that they want. By the end of the game they should have all nine, however, as the blades will level up, those that they have had the longest are likely to be the strongest.
So you can see that the blades will be crucial to the game. There won't be any other types of weapon for the time being, however some spells might be added. The stick is the first weapon the player will get but it doesn't count as a blade and I'm considering making it break as a story element early on.
Anyway. All there is to say for now :)