Just hit 80
Yes you need to unlock Glint: is one of the most useful legends and meta in pretty much every game mode. The total cost of the full specialization is 250 hero points (albeit you can get access to the new F2 feature and shield wielding with only ~50 hp spent-, but you can get them easily -and fast- in the first two maps of the expansion (Verdand Brink and uric Basin), which are the most farmed ones. Shiro Mallyx is still a good combo, specially with a condition damage build, but Shiro Glint (sometimes Jalis Glint) is even better, with power (direct physical damage) stats.
Yes, absolutely unlock Glint, go in the new zones and start doing hero points:
if you already have 90 points you will unlock all the skills pretty soon.
norn warrior