With mediocre enhanced effect which would be better? Is there a real difference?

Regular weps you can have an action (attack,heal,town,etc) every 1 second, with heavy weapons it is 2 seconds.

Because you hit half as many times with heavy weapons, its similar to saying the enemies armor is only 50% effective as it is for normal weapons.

But, heavy weapons have a big draw back too. The 2 second delay could really mess you up with trying to leave catacombs and mix that in with monster abilities and things can get dicey.

Also heavies are much more rare which means more expensive.

heavy weapons do more overall dmg.. since you can do more than just 50% of the actions of a normal weapon.
example: new wave spawns: you got heavy i got normal weapon.. you can still be faster than me and attack the monster. so you got +1 action and i still have 0 ^^ if we both have more time to hit several monsters i you should have around half of my actions.
heavy weapons might waste more dmg since they overkill the monster a lot more often (like 1000 dmg on 500life monster)
i myself like heavy weapons.. they have their pro and cons.
gear wise the best heavy weapon is a battle axe since you can just use it instead of a normal axe. you cant use spears instead of daggers for example since sammy cant use them.

A heavy weapon is strong but reduces character speed.. I'd hold one in your inventory while your traveling.