This isn't a very PvP centric game, I'm not entirely sure what this "shield" is supposed to protect them from.
Plunder? Well, there is already a 15 level limit on that, so any new player won't get plundered in any remotely seasoned server as their level would be too low.
Sage? Well, sure, you can in theory protect them in sage from the big ones, but that's fairly pointless considering there probably won't be exactly a lot of target for them to hit anyway (fellow shielder) or do you mean that they can challenge the big ones at their leisure but the big ones can't hunt them back? That's silly and unhelpful(since they lose anyway) and would only lead to alt-win-feeders.
Red name? Well, they won't be red cause they won't be able to plunder in any reasonably seasoned server.
Ranked? Well, for one it's ranked so it would be rather unfair for them to have protection there. But frankly, no one really care about ranks and for the first couple days, they'd be trying to climb out of the pit of abandoned characters, so they won't be anywhere challenge is likely to happen anyway.
Masuri? In theory it would be more fair to match player of similar age in masuri, but that probably doesn't need anything of this sort but rather just a masuri matchmaking change.

So overall, such a "shield" does pretty much nothing. You know what kind of game the shields are used for? Ones where you can be attacked at any time by anybody otherwise. Because without the shield, you'd be "killed" before getting anywhere. Since the attacking anyone at anytime thing doesn't really exist in this game, a shield against it would be superfluous and accomplish nothing.