Barberry - slow to ramify, painful to touch. Some people clip the thorns off before wiring, but that seems like a lot of work. Mine are in a Turface/Pumice/Akadama mix at 70/20/10 proportion. Water every day, do not let dry out. A dry barberry in a pot can be a dead one. I would rub those buds off the trunk, but save some, your tree looks like it could use a few extra branches. I feed organic mostly - the leaves don't seem to like a lot of chemical fertilizer. Full sun. I will post a few pics of my berberis when I get a chance, thanks.