Yeah, the 8-bit sword was released back in update v1.2.0, so I figured the others would be the same as it. If you think about it, they have to be the same power as one of the base weapons to avoid "pay to win". They did the same with MK8 - all the DLC karts are clones stat-wise of other karts. ...Of course, if you REALLY think about it, that doesn't matter in a game with no online multiplayer. Also, the fact that Cia/Volga/Wizzro's L2/L3 weapons are unlocked in the MQ map is kinda weird.
Like you, I'm also not bothering with heart containers for most characters until later. I got all the weapons and gold skulltulas in the adventure map, so I went ahead and moved on to the MQ map. I'll come back for the rest of the heart containers when I'm done with that and all my warriors (*cough* Agitha) are stronger.