Coulson identifies Professor Randolph's pen as a "Waterfield '44 with a 14ct nib and mother of pearl inlay." If a company named Waterfield that made fountain pens existed, there appears to be no remaining evidence of it. 14ct nibs were typical for any but budget models during the era of fountain pens, making that an easy guess for Coulson. The pen in the show is made from celluloid in an iridescent pattern, which is commonly called mother of pearl, but there's no inlay. Based on its limited on-screen exposure it appears to be a 1930s-era Gold Bond with a lever filler (also very common at that time). Additionally, as of the episode's air date and excluding particularly rare models, a vintage fountain pen is easily within a professor's or a federal agent's salary.
Ming-Na Wen is 20 years older than Brett Dalton, making it a May-December relationship (no pun intended).