There is no cap and you always get bonuses but they become irrelevant after 310. The first 5 are actually the most valuable, while 6-10 is optional (not important). 11+ is a waste of stats.
As for your gear, you don’t want that dagger regardless because the 2 from AV are your best. Take the belt, then get the glove from MC when you can. It’s pretty easy to get because it can drop from numerous bosses and not many others will be after it. Guilds give priority to dagger rogues.