Buying, Finding, and Using New Equipment

Are you solely limited to the equipment found in the initial equipment list for your warband? For example, the norsemen have access to light armor initially, but not heavy. does this mean that if i come across some heavy armor, i cannot use it?

also, for the use, and seeking out of rare items: some denote a particular faction (such as the skaven's claws) while others do not. are there general rare weapons that are usable by any faction?

If a player wants to buy new weapons or other equipment for existing warriors, refer to the Price chart in the rulebook. The chart lists all the equipment available in Mordheim, not just the common weapons included in the Recruitment charts. Rare items and weapons are not always available and vary in price. Remember that your warriors lack the skill to use any weapons other than the ones listed in their entry under your warbands Recruitment charts. You may still want to buy rare items offered to you, as your warriors may be able to use them as they gain in experience. Players should preferably complete any recruiting and trading after the battle is over, making the appropriate dice rolls whilst both players are present. However, some players may prefer to wait until the heat of battle has cooled and they are able to consider purchases more carefully. Determine which rare items are offered for sale while both players are together. The players can work out what they will buy later.

So if I have swords avaliable to me, I can use all rare swords? Like if I wanted a swordbreaker, all I'd have to do is roll above an 8 on 2d6 with a hero and I could buy it?

No. Guys may only use equipment they could have started with unless they gain a skill to allow them to use something different.