I disabled the Tinkers' Weaponry module in the the tinkers' construct config file.
After starting the game i tried to mine a cobblestone in singleplayer and my game crashed.
I read the crash report
crash-2017-03-04_09.01.14-client.txt
and then looked at the line of code mentioned in the crash report: iguanaman.iguanatweakstconstruct.leveling.RandomBonuses.(RandomBonuses.java:75).
The line is:
modCache.put(TinkerWeaponry.modAttack.key + "Ammo", TinkerWeaponry.modAttack);
(URL: https://github.com/SlimeKnights/IguanaTweaksTConstruct/blob/master/src/main/java/iguanaman/iguanatweakstconstruct/leveling/RandomBonuses.java)
Because of this i think, that the crash has something to do with the disabled module.

Maybe you can fix this by first checking if the module is there and then executing the line of code. If the module is disabled i would simply ignore it.

ITT is not developed anymore, just don't disable the weaponry module.