Ron Guth:
To continue publicizing the increase in the weight of the Dimes that took place in 1873, the Mint used arrowheads again in 1874 on either side of the date to differentiate the new coins from the older, lighter-weight coins.
Though the mintage of the 1874 With Arrows Dime was only slightly above that of the 1873, the former is more readily available in Mint State than the latter, and it is easier to find in super-grades (MS67 and better). In fact, the finest example of the 1874 With Arrows Dime is an amazing PCGS MS68+, which is easily the best example of this short-lived type.