Thats alt shards bud, if you hold the ALT key while mousing over a weapon it will tell you more advanced information about it - specifically the tier and ranges of the prefix/suffixes. Rule of thumb, if it isnt loaded with high rolled t3's or better, or dosent have the perfect stat combos i.e phys%/flat phys/as/crit/crit multi its trash
99.99% of everything you ever pick up will go to a vendor. Sad fact of poe