One also asked elsewhere:
All good questions. It all depends on to what criteria or purpose one is designing the structure or object, i.e. is the goal to resistant deformation/fracture under high strain rate, or fracture or disintegration is desirable. These two goals refer to armour (resistant) or armour-piercing.
To resist failure, the material needs high strength (high YS and UTS), high fracture toughness, and high ductility, and the ability to achieve a maximum strain energy density (SED), which is basically the integral under stress-strain curve (maximum energy absorption without or before failure).