muscels build up to what u want them to do... if u want to build up fast muscles then do fast exercises... if u want slow but powerful then do weight training... etc. as far as hardening goes... ur body is great at adapting. y do u want them hard? so u can take hits?? if u want to take hit s then take hits and the'll grow stronger and harder and bruise less... making ur body adpat to what u want it to do is by far the eisiest and cheapest way...

Lifting weights doesnt make you slower.
Also, getting hit wont make your muscles any harder. Getting hit isnt the easiest way to get strong, lifting weights will.