altiar(assasin/cleric D&D 5e) an idea

The balance is way off in that you are giving the class way too much in all catagories.

For example you have two strong saves. Strong or commonly uses saves are Dex, Con and Wiz. If you look closely you will noticed every class has one of them and one other. So I would have to say pick either Dex and Chr or Wiz and Int but make it only those and not the option of either or.

Armour proficiency: should not be limited to a single type and instead should be just light armour.
Weapon Proficiency: once again make it simple plus hand crossbow and rapier. More in tune with rogue.

Skills: Pick three from Acrobatic, religion, medicine, insight, persuasion, stealth and investigate.
Tools: Pick one of thieves tools or med kit.

I understand the flavour of the blessed silver weapon but it is a special weapon and as such more powerful then what someone would start with as it is almost a straight weapon +2 as it applies to all damage. I would recommend changing it to an ability gained at second level or something.

e.g. at second level they gain the ability once per long rest to bless their weapon as a free action. For the next 10 rnds a successful hit does an addition 2 points of damage (could balance this against a barbarians rage damage. Don't have the book with me currently to do so.
You need to reword the minor spell casting/sneak damage as well. And the ability to gain 2 feats as 6th level is super over powered as I have seen a lot of 10th level character with no feats as they are so powerful and suppose to be really rare. I would advise to simply remove this completely and balance out the other great abilities.