In Brief: Sailor Mars' first attack, while very powerful and used very often appears to only have one, ironic use; firepower. Consisting of a pure fire energy blast, Mars Fire Ignite helped up the team's offensive power in almost any battle Mars was in, especially in the number of arcs which featured Sailor Moon, Mercury and Mars before Sailor Jupiter and Venus joined up.

Cultural: Fire seems to symbolise in almost every culture, purification and rebirth both physically and/or spiritually and can also be seen as a living entity through which wisdom can be gained (think Raye's firereading or Moses' burning bush and the famous writing on the wall in The (Christian) Bible).
Fire can also be seen to represent destruction and chaos or even war and when you think of the who the Roman god of war is (Mars or in the Greek, Aries) fire seems to have even greater meaning for the character of Sailor Mars.

The Attack: Sailor Mars simply summons the attack causing fire to burst from her hands.