A player generally has 3 combat weapon choices when using ground weapons. The first weapon is an equipped ranged weapon with has two types of attacks. The primary attack, is a direct attack, such as phaser fire. The secondary attack is a larger ability like sniper or cone attacks where you can either deal heavy concentrated damage to a single or multiple targets. The third attack is a skill attack such as photon grenade, smoke grenade, gas grenade, mine laying, phaser turrets, etc. It is possible to have more than one skill attack in your skill bar, so in effect, the limit of attacks you have are the attack skills you possess. Another skill attack is the melee attack such as the leg sweep, rifle butt or other martial art.
You may also have the choice of melee weapons such as a Klingon Bat'leth, or utilizing martial arts.