The Squire's Helm isn't a bad card in isolation. Two hit points are great on your high value low HP allies who you don't want dying because of some surprise treachery or more commonly, shadow effect. I particularly like this with Defender of Rammas which gives a lot more longevity for a cheap but valuable card.
Problem is, since I obtained Hauberk of Mail, I haven't really been able to justify this card too often; just seems more tangible than in a lot of scenarios. And if you're buffing up a high value ally, do you really want to use up your valuable restricted slots on a cheap helmet?