These models seem be very well suited for a mobile game, they are quite detailed but relatively low poly also. For a mobile game especially these are very well suited for the environment. If this were to be used for PC game these would be much more inappropriate but due to the major restrictions this form of modelling can be quite beneficial performance wise (the texturing comes out quite well so the look of the game does not suffer either). For gaming specifically it is more texturing that you would have to worry about rather than the model itself (performance is usually affected by texture quality rather than the derivative shapes of the game objects). For the usability in unity the sword and shield are quite simple, this is good as something like an inventory system would benefit from the simplicity of the models as they would not be resource intensive to spawn in (this refers to the type of modelling in general rather than the specific items in the said model). Overall, for a MOBILE game these are great models and would work well in the engine and provide an excellent balance between aesthetics and performance. For rigging it is just simpler as one cube = one bone but I will leave this open for someone else to chime in about the rigging aspect. There is my two cents worth, Happy Blending! :)