Is there a weapon skill cap? 308?

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.

The only weapon type with any sort of options in how you get the weapon skill is daggers. You option for ax/sword skill comes in chunks of 4, 6, or 7. You’ll see most people settle on a sweet spot of 307, 309, or 311 because of how much weapon skill is on items with weapon skill.