In order to increase both offensive and defensive capabilities in hand to hand combat, what would be some defensive and offensive maneuvers we might observe in a soldier with indestructible bones?
Not much would change, save that the enemy has to take a better aim.
The other organs are still exposed. The ribcage will not cover 100% of heart and lungs, and even if the spine's vertebrae are indestructible, they still could be bent to the point of causing internal damage.
An explosion will cause massive internal trauma, minus the fractures. And, funny enough, indestructible bones of the skull means that the shock from a clubbing will trasnsmit more efficaciously to the brain, since that now the skull won't absorb part of the impact. That is why cars can crash apparently so easily -to disperse kinetic energy.
Going for the soft bits stops being a preference like it is in normal hand-to-hand, it's surprisingly easy to break your hand if you use a closed fist on someone's face, and becomes a necessity. Not because you can damage yourself on areas with bone close to the surface but because you can't damage those parts of your opponent any more. The gut, throat and solar plexus become prime targets, more so than they already are, for barehanded strikes. With weapons the areas where arteries are close to the surface, the upper arm, wrist, and to a lesser extent the thigh become even more important both to the attacker and the defender. Body armour will therefore concentrate more on areas with more flesh than bone rather than on vital organ coverage but in reality what's already important is just more important. Strikes aimed at areas like the rib cage will have to be even more accurate than they already need to be to do any damage since bone won't part for a sloppy but forceful blow.
In my opinion not much would change in offensive manuevers, because afaik most melee attacks are not directed at the bones, but at the more vulnerable tissue / organs. The exception (as already answered) might be the skull.
Most popular defensive maneuver:
- Kill one enemy, possibly via overwhelming force.
- Remove fleshy parts and organs.
- Build armor out of his/her bones.