Pointed Discussion

Hanna's Custody is better.

Hanna's Custody, being an enchantment, is generally seen something different.
Leonin Abunas, however, is a strictly better creature than that guy when disregarding creature types: It only requires a single white mana, has 2 more toughness, the static ability is unconditional (doesn't wear off when tapped), and you can still target your artifacts as desired.
(But you're also right because of the fact that finding creature removal is always easier than finding enchantment removal)

This is Guardian Beast version 2.0. This was printed in Mirage, at a time when Wizards was *terrified* of hypothetical shroud abuse. They were worried that A gives shroud to B + B gives shroud to A would result in an unbreakable lock by turn 4 or 5, basically. This was in the days before combo decks could reliably produce a third-turn kill, when the Stasis lock was universally reviled as eeeevil. Black had Guardian Beast and Sinkhole. White had Swords to Plowshares and Balance. In theory, Spectral Guide could have tilted what was at the time a fairly delicate balance.

It took Wizards quite a while to realize it was perfectly alright for one card to protect another class of cards, that this could be normal (and was more natural for than for as the core protective color; if Guardian Beast was printed nowadays it would have been .). Compare to Fountain Watch -- by the Mercadian Masques era, mass shroud was tried, tested, and proven (for a fairly high casting cost). Who paved the way for that? Spectral Guide, that's who.

3/5 for its historical significance alone! :)