Guardians are the main-line forces of the Aeldari and have been for quite some time. These troops are getting an update in the new codex coming soon for the faction, just like everything else. Get a look at how they'll be changing in this preview.
From the article:
The Aeldari are a dwindling race, so to maintain an effective fighting force every craftworld must draft its butchers, bakers, and candlestick makers into a local militia. Formed into units of Guardians, these citizens take up arms in times of war, providing battlefield support to dedicated Aspect Warriors as infantry and vehicle crews.
Aeldari seldom do things by halves – despite being a militia, each Guardian is a highly trained match for the most elite of the Imperium’s soldiers. The upcoming Codex: Aeldari gives them the boost they need to put on their war face* and go toe-to-toe with the galaxy’s threats.
Guardian armour is tougher. This reactive thermoplas mesh now grants its wearer a respectable 4+ Save characteristic – without compromising the flexibility they need to pull off acrobatic Battle Focus moves.