Technical issues for walkers and scramblers
Although helmets have not traditionally been worn for walking or scrambling, they are becoming increasingly more common, especially in winter. Many walking injuries are head injuries caused by falling, slipping, being blown off exposed paths, or by rocks falling due to thawing snow or ice, or from parties scrambling above. The modern style of foam helmet (Petzl, Grivel, Black Diamond) is very light, both on your head and in your rucksack. They give good protection in both the event of a fall and from falling rocks.
Look for a model that can be worn over a hat or balaclava, and choose a model that fits comfortably and securely. In winter it may be worth taping over any ventilation holes to limit heat losses (and to avoid the 'pan pipe' effect of the wind blowing through your head!) Most helmet designs also accept a head torch.
Karabiners come in many different sizes, shapes and designs, but for scrambling only two are relevant. Firstly the HMS, a large-capacity screwgate, which can be used for belaying in two ways: firstly obviously with a belay device but it's also wide enough to allow belaying using an Italian hitch knot.
Non-locking straight gate karabiners are simple, light and the foundation of your rack. They are your primary attachment system, joining running belays to the rope. These are the 'glue' that holds the climb together. The modern wire-gated models are perhaps the most appropriate for walking and scrambling, being very light, strong and resistant to snow or ice jamming the gates shut.
Slings are used in partnership with the rope to achieve secure running belays. They are generally pre-sewn lengths of full strength climbing tape, formed into a loop (about 60 cm) that can be easily carried over the shoulder. In use they are draped over spikes, or wrapped around blocks and chock stones and clipped into the rope via a snap gate karabiner or screwgate. The best material for slings is Dyneema, it's very similar to Spectre, is lightweight, resistant to abrasion and stronger than steel! Dyneema slings are also very resistant to freezing, so they rarely become stiff or unmanageable.
Confidence ropes are the same as dynamic climbing ropes, but are generally shorter and of a smaller diameter than those usually chosen by climbers. Ropes can safeguard both the leader and follower, and they can be used in conjunction with slings, nuts and karabiners. By using a rope a team can descend over steep ground safely, where it would otherwise be too dangerous to down climb unassisted. A confident leader can also use the rope as a safety rein, to provide an unsure second with some extra some confidence and safeguard them on exposed sections.