I made up for my lack of dex by utilizing level 1 Invoke and dex accessories
Guardian Class: The Guardian Class is known as the warrior class of the Rohan. The complete opposite of defender, their power lies on their offensive attacks. Now here is a guide for Cabal online Alz Guardian. Just go through.
Base Stats - Strength Build: Most people follow a 3:1 strength to vit build. This is a good starting point as you will do pretty decent damage with decent gears as well as have the HP boost to survive while grinding. However, as strength build you still need to accommodate for dex in your build so that you can hit mobs every hit without missing.
Personally, I stayed with base dex all the way up until level 60 where I was able to use four Wings of Solemn Death (15 strength, vit, dex). I made up for my lack of dex by utilizing level 1 Invoke (20% boost) and dex accessories.
If you are not a member of the Exchange Market, I suggest still using dex accessories so that if you ever do get your hands on a Wings of Solemn Death, you do not have too much dex (unless you wish to have it that way, I know many Guardians who do).