At first glance the array of ice axes on display in a climbing shop may seem bewildering, but there are actually only three types of axe: these are: Walking Axes, Alpine Axes and Technical Axes.
Walking Axes: These are used singley and are primarily for support on steeper ground where they can be plunged into the snow. The secondary use is for fall arrest (also known as ice axe braking) where the pick is dragged into the snow as you slide down a slope to save you from being swept over a cliff or into a pile of boulders - this needs practicing on a safe slope!
Alpine Axes: These are leashed axes with stronger more steeply curved picks than walking axes, making them the ideal choice for the climber doing easier snow climbs and alpine routes, or the walker who aspires to. There are very light versions available for ski mountaineering and high altitude use but these are not durable enough for the UK.
Technical Axes: Axes that are designed to be used without leashes for steep ice and mixed ground. Some of these may be able to have leashes fitted and some can be stripped down for alpine climbing. Some are intended for pure water ice, others for hard Continental style mixed routes and the majority can be used on either and are particularly suitable for Scottish mixed. They tend to be very wiggly and have lots of advantages if you are climbing high in the grades but a few disadvantages if you are not (such as being short in length, not very easy to plunge into heavy snow, and having no adze or hammer in some instances - we have labelled these latter 'Blank'). Any alpinist climbing at D and above will probably prefer to use a pair of technical tools rather than a traditional alpine axe and hammer.
How to pick a climbing axe (if you'll forgive the pun) is one of the more difficult questions that faces the would be winter climber. What feels right to you is likely to feel very wrong to the next person. If you are unable to borrow axes to try before you buy, then the following may help.
Think of an axe as a weight on the end of a long stick. Hold the shaft right at its base (this is where you would normally hold an axe when winter climbing) and wave the tool in the air. If it feels heavy and unwieldy or alternatively light and insubstantial then try a different model or try different shaft lengths of the same model. Basically what feels correct is a function of your own strength. Buy an axe that is too heavy and you will get pumped half-way up a pitch; buy one that is too light and you will curse as it bounces off hard ice! Needless to say it is rather difficult to do this over the internet...
'T' & 'B' Ratings: Ice axes are either 'T' or 'B' Rated. T rated means that the shafts are strong enough to belay from while B Rated means they are not; nearly all climbing axes are 'T' rated. Confusingly though picks for ice axes are also either 'T' or 'B' rated. 'T' rated picks are heavier duty and are designed for Scottish winter and alpine mixed climbing, but are also suitable for icefalls, whilst 'B' rated picks have finer blades and are only suitable for pure water ice climbing. For UK use we would recommend the use of 'T' rated picks as 'B' rated picks may not be strong enough for mixed climbing.
Recently, B and T Ratings have been superseded by new EN Ratings, Type 1 and Type 2:
Both have the same test and strength requirement for the shaft strength test, which was originally the B rating (which best simulates the buried axe/T-Slot technique). Where the differences between Type 1 and 2 become more obvious is in the lab tests that try to simulate torquing/stein pulling and really test the strength of the pick and the pick-shaft interface, with the loads required for Type 2 tools being significantly higher.
So, in summary:
Type 1: Standard walking and alpine mountaineering axes, suitable for ice axe belaying, but not designed for hard modern mixed climbing involving torquing picks etc.
Type 2: Modern leashless tools suitable for ice axe belaying, and also designed for hard modern mixed climbing involving torquing picks etc.