General - Weapon/Equipment Restrictions
Your kit is primarily defined by your role, which is stated on the roster.
As such you can see the applicable primary arm on the individual role page.
Aside from that, your kit will be determined by the needs of the mission at hand and as such, it is primarily determined by either you immediate superior, or someone higher up the chain of command.
Thus, any equipment changes have to be cleared through your proper chain of command.
Often, another determining factor of your kit will be the mission design itself, determined by the mission maker. The mission maker may place certain restrictions on the available equipment or weaponry for reasons of roleplay or gameplay.