Recently, Sanguine's Rose ran out of charge for me, as well as several weapons that I use. I have tried to utilize the Black Star and soul gems to try and refill the weapons, but they seem to not be working... is this a bug, or am I doing this wrong?

Thank you in advance for your help.

You need to have a filled soul gem. When you look at it in your inventory it will show whether its filled. In your weapons inventory, highlight the item you want to charge, then press the corresponding charge button found at the bottom lower left of the screen(pc its the T button to charge).

If you have the star all you need to do is fill it with a soul (you have the black version so only humanoid souls can go in there) by casting soul trap (or having it on your weapon as an enchantment) and killing the enemy while they are affected with soultrap.

You can also buy soul gems from vendors which are filled, and all you need is one grand soul gem for a fill up.

Ah, thank you for that. It's been puzzling me for awhile now. Thanks.