This is question was inspired by a similar one in /r/history that did not get a satisfying answer.
We certainly do, and the evidence suggests that while Joan led from the front, she did not attempt to kill people. The survival of records from her 1431 trial for heresy in Rouen and the subsequent nullification trial of that from 1455-56 give us lots of information about what Joan was like, from both herself and from contemporaries. None of it can be accepted uncritically, but that doesn't mean it's not useful.
Was Joan a killer?
Almost certainly not. The fourth public examination in the Rouen trial records Joan defending her record like this:
Asked about which she preferred, either her standard or the sword, she answered that she liked her standard four times as much as her sword...She also said that she herself carried the standard when she was attacking the enemy, in order to avoid killing anyone; and she said that she never killed anyone.
I can go into more detail on the process of recording the trial, but there's no reason to think this line was doctored. From a common sense point of view, it makes no sense to edit Joan from a killer to a non-killer, as the aim of the trial was to convict Joan of heresy and the aim of the record was to legitimise that conviction to the educated public.
Was Joan on the front lines?
Yes. Bearing aside all discussions about the armour Charles VII gave to her, her use of swords, and her battle standard, let's look at the times injury is recorded in the primary sources. Injury indicates some proximity, but more helpfully it creates a picture of what Joan was doing. The nature of all three injuries (from range) also gives the impression she was not within sword's reach, which is why I'm using this list to answer your question.
Some of these sources call Joan 'the Pucelle', which is typically translated as 'the Maid'. It suggests a particular age and purity: unmarried, but eligible, young and (importantly for contemporaries) a virgin. It's also worth noting that some witnesses at the nullification trial, if they were witnessing in the same city, may well have done so in public next to the other witnesses, so their stories could have influenced each other. They were also all doing it at least 25 years after the events!
Orleans
First off, she was injured by an arrow at the siege of Orleans, while assaulting a stronghold known as 'the Tourelles'. The Rouen trial record has Joan saying that :
...at the assault made upon the fortress of the bridge [the Tourelles], she was wounded in the neck by an arrow or crossbolt...as she was lifting the ladder, she was wounded in the neck...
Speaking in 1456, the Count of Dunois at the nullification trial said that:
...at the start of the assault against the enemy defending the boulevard of the bridge, Joan was wounded by an arrow which penetrated six inches into the flesh between the neck and shoulder.
As part of the same trial, Jean Luillier, a burgher of Orleans, is recorded saying:
...an assault was made against the enemy found in the boulevard of the bridge. It was said that during this attack she had been wounded by an arrow.
Also in the same trial, although witnessing at Paris, Louis de Coutes states:
The King's men continued to attack the place...until night. Joan was wounded and her armour was removed in order to treat her wound; as soon as it had been treated, she put on her armour again and went with the others to the attack and assault...
Jean Pasquerel, another witness at Paris, said:
...Joan went to the assault on the fortress of the bridge...In this assault, after dinner, Joan was struck by an arrow above her breast as she had predicted. ...she was wounded in the shoulder by a crossbow bolt so that the bolt went through from one side to the other...
Finally in 1467 the anonymous Journal du siege d'Orleans records that:
...among the others wounded there [was] the Pucelle, struck by an arrow between the shoulder and the throat so deeply that it passed right through.
Jargeau
Another injury is mentioned as happening while taking Jargeau. The Duke of Alencon is recorded in 1456 as saying:
Joan was on a ladder, holding her standard in her hand, when it was struck and she herself was hit on the head by a stone which broke her helmet.
Obviously since the Duke is the only one mentioning this, it's worth taking it with a pinch of salt.
Paris
She was also injured at Paris. In September 1429, Clement de Fauquembergue wrote:
...among them a woman known as the Pucelle was wounded in the leg by an arrow; she led the army with the other captains of my lord Charles of Valois, who expected to harm Paris...
The Rouen trial records Joan saying that:
...she was wounded in the trenches before Paris, where she had arrived after coming fromt he town of Saint-Denis; but in five days she was healed...
An eyewitness to the siege of Paris, writing around 1431, wrote in his journal:
'See here, you whore, you slut [paillarde, ribaulde]!' said one, and he shot his crossbow straight at her, and [the bolt] went right through her leg, and she fled.
Jean Chartier's chronicle of Charles VII, written around 1445-1450, records that:
...she went with a very great force of men-at-arms...and there Joan was wounded by an arrow in the leg.
The chronicle of Enguerrand de Monstrelet, written around 1447:
...the Pucelle was very gravely wounded, and she remained the whole of the day in the ditches behind a small mound, until vespers, when Guichard de Chiembronne and other came to find her.
All sources are quoted from Craig Taylor, Joan of Arc: La Pucelle (Manchester: Manchester University Press, 2006), which is a sourcebook with many of the most important sources on Joan of Arc translated into English.
We actually have an entire section of our FAQ devoted to Joan of Arc! You would probably be especially interested in: