Since the dragon lives in a forest, he limits the use of his acidic breath weapon on home ground to hit 'n run, supply destruction, and a way to deter his enemies and give him a chance to escape.
There is also the potential of a severe heartburn if he overused it. Consequently, dragons should have a secondary weapon, they can rely upon when fighting.
Thanks to their armor and size (190 cm at the withers), dragons would be apex predators if it wasn't for humans, more precisely, knights. Though HCl and HNO3 are capable of destroying a knight's armor they usually wear chainmail AND a gambeson underneath, leaving the rather significant fumes of the acids as the most imminent threat.
Still, I hate taking chances, so my dragons will have more "traditional" natural weapons, the problem with that is their limit on muscle-mass, imposed by their flight muscles (which has to be 25% of the TOTAL bodymass).
But dragons would need to hit hard, since the best way to defeat armored opponents is with bike locks or sheer force.
It'd be preferable if they didn't leave themselves wide-open when attacking, like stretching the neck to the point where it begs to be cut. Dragons hate putting their lives in danger when not necessary, and are rather squirmy and jumpy.
A suitable natural weapon:
- Is able to effectively harm even human knights
- Needs little muscle mass, but produces significant forces
- When attacking with it, the dragon doesn't leave himself open to an attack, either from the same or other opponents.
Three additional notes:
- Dragons are able to perfectly recover from any injury (that isn't brain damage), as long as they're alive (so they're just as good at it as axolotls)
- Dragons have six limbs (four legs (the front legs are for climbing) and a pair of wings)
- Skallagrim did a video on why it's important to be wide as well as having logs for arms. Though this applies to humans, I wonder if there's something similar with animals. After all, you use a lot of muscles when attacking.
Considering the above, what's the most suitable physical (so whacking, hacking and thrusting) natural weapon for dragons? You're allowed to redesign the limbs, as long as they fulfill their intended purpose.