well, it depends. since you are strictly going for direct damage it seems i would go with a sigil of fire to add some dps. im not a huge fan of the stacking sigils (though i use a sigil of corruption myself) since it is quite easy to lose the stacks in a dungeon, but it certainly is an option, and its quite a good one. you could also go for the sigil of accuracy or strength (5% damage or precision).
as for your armor, if you feel tht you are survivable as is, id say runes of divinity, +60 to all stats and 18% (i know that it says +2% crit damage per rune but you also get +60 stat points of crit damage which is another 6%) crit damage is nothing to sneeze at though they come at a hefty price.
there is also runes of the eagle and scholar. while you can go for boon duration, you arent really a boon churning machine like an ele who is specced into arcana (which i dont know how you live without ) so those are kinda worthless to you. all the above options (divinity, eagle and scholar) are the ones that will increase your damage the most since you dont seem to want condition damage. beware they are all expensive. if you cant afford the superior versions id get 4 major of 1 and 2 majors of another and then slowly upgrade them as i got money.
Thank you again for your generous advice. After you mention it, stacking sigils are quite a liability since its quite easy to lose those stacks. Good point.
I would like to try giving out boons but I do not know how they work. And I sometimes play with a PUG where there are others who stack conditions so is it redundant for me to go for condition damage?